]>
Commit | Line | Data |
---|---|---|
1 | /* A state machine for detecting misuses of the malloc/free API. | |
2 | Copyright (C) 2019-2024 Free Software Foundation, Inc. | |
3 | Contributed by David Malcolm <dmalcolm@redhat.com>. | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 3, or (at your option) | |
10 | any later version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING3. If not see | |
19 | <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #include "config.h" | |
22 | #define INCLUDE_MEMORY | |
23 | #include "system.h" | |
24 | #include "coretypes.h" | |
25 | #include "make-unique.h" | |
26 | #include "tree.h" | |
27 | #include "function.h" | |
28 | #include "basic-block.h" | |
29 | #include "gimple.h" | |
30 | #include "options.h" | |
31 | #include "bitmap.h" | |
32 | #include "diagnostic-path.h" | |
33 | #include "analyzer/analyzer.h" | |
34 | #include "diagnostic-event-id.h" | |
35 | #include "analyzer/analyzer-logging.h" | |
36 | #include "analyzer/sm.h" | |
37 | #include "analyzer/pending-diagnostic.h" | |
38 | #include "analyzer/call-string.h" | |
39 | #include "analyzer/program-point.h" | |
40 | #include "analyzer/store.h" | |
41 | #include "analyzer/region-model.h" | |
42 | #include "analyzer/call-details.h" | |
43 | #include "stringpool.h" | |
44 | #include "attribs.h" | |
45 | #include "analyzer/function-set.h" | |
46 | #include "analyzer/program-state.h" | |
47 | #include "analyzer/checker-event.h" | |
48 | #include "analyzer/exploded-graph.h" | |
49 | ||
50 | #if ENABLE_ANALYZER | |
51 | ||
52 | namespace ana { | |
53 | ||
54 | namespace { | |
55 | ||
56 | /* This state machine and its various support classes track allocations | |
57 | and deallocations. | |
58 | ||
59 | It has a few standard allocation/deallocation pairs (e.g. new/delete), | |
60 | and also supports user-defined ones via | |
61 | __attribute__ ((malloc(DEALLOCATOR))). | |
62 | ||
63 | There can be more than one valid deallocator for a given allocator, | |
64 | for example: | |
65 | __attribute__ ((malloc (fclose))) | |
66 | __attribute__ ((malloc (freopen, 3))) | |
67 | FILE* fopen (const char*, const char*); | |
68 | A deallocator_set represents a particular set of valid deallocators. | |
69 | ||
70 | We track the expected deallocator_set for a value, but not the allocation | |
71 | function - there could be more than one allocator per deallocator_set. | |
72 | For example, there could be dozens of allocators for "free" beyond just | |
73 | malloc e.g. calloc, xstrdup, etc. We don't want to explode the number | |
74 | of states by tracking individual allocators in the exploded graph; | |
75 | we merely want to track "this value expects to have 'free' called on it". | |
76 | Perhaps we can reconstruct which allocator was used later, when emitting | |
77 | the path, if it's necessary for precision of wording of diagnostics. */ | |
78 | ||
79 | class deallocator; | |
80 | class deallocator_set; | |
81 | class malloc_state_machine; | |
82 | ||
83 | /* An enum for discriminating between different kinds of allocation_state. */ | |
84 | ||
85 | enum resource_state | |
86 | { | |
87 | /* States that are independent of allocator/deallocator. */ | |
88 | ||
89 | /* The start state. */ | |
90 | RS_START, | |
91 | ||
92 | /* State for a pointer that's been unconditionally dereferenced. */ | |
93 | RS_ASSUMED_NON_NULL, | |
94 | ||
95 | /* State for a pointer that's known to be NULL. */ | |
96 | RS_NULL, | |
97 | ||
98 | /* State for a pointer that's known to not be on the heap (e.g. to a local | |
99 | or global). */ | |
100 | RS_NON_HEAP, | |
101 | ||
102 | /* Stop state, for pointers we don't want to track any more. */ | |
103 | RS_STOP, | |
104 | ||
105 | /* States that relate to a specific deallocator_set. */ | |
106 | ||
107 | /* State for a pointer returned from an allocator that hasn't | |
108 | been checked for NULL. | |
109 | It could be a pointer to heap-allocated memory, or could be NULL. */ | |
110 | RS_UNCHECKED, | |
111 | ||
112 | /* State for a pointer returned from an allocator, | |
113 | known to be non-NULL. */ | |
114 | RS_NONNULL, | |
115 | ||
116 | /* State for a pointer passed to a deallocator. */ | |
117 | RS_FREED | |
118 | }; | |
119 | ||
120 | /* Custom state subclass, which can optionally refer to an a | |
121 | deallocator_set. */ | |
122 | ||
123 | struct allocation_state : public state_machine::state | |
124 | { | |
125 | allocation_state (const char *name, unsigned id, | |
126 | enum resource_state rs, | |
127 | const deallocator_set *deallocators, | |
128 | const deallocator *deallocator) | |
129 | : state (name, id), m_rs (rs), | |
130 | m_deallocators (deallocators), | |
131 | m_deallocator (deallocator) | |
132 | {} | |
133 | ||
134 | void dump_to_pp (pretty_printer *pp) const override; | |
135 | ||
136 | const allocation_state *get_nonnull () const; | |
137 | ||
138 | enum resource_state m_rs; | |
139 | const deallocator_set *m_deallocators; | |
140 | const deallocator *m_deallocator; | |
141 | }; | |
142 | ||
143 | /* Custom state subclass, for the "assumed-non-null" state | |
144 | where the assumption happens in a particular frame. */ | |
145 | ||
146 | struct assumed_non_null_state : public allocation_state | |
147 | { | |
148 | assumed_non_null_state (const char *name, unsigned id, | |
149 | const frame_region *frame) | |
150 | : allocation_state (name, id, RS_ASSUMED_NON_NULL, | |
151 | NULL, NULL), | |
152 | m_frame (frame) | |
153 | { | |
154 | gcc_assert (m_frame); | |
155 | } | |
156 | ||
157 | void dump_to_pp (pretty_printer *pp) const final override; | |
158 | ||
159 | const frame_region *m_frame; | |
160 | }; | |
161 | ||
162 | /* An enum for choosing which wording to use in various diagnostics | |
163 | when describing deallocations. */ | |
164 | ||
165 | enum wording | |
166 | { | |
167 | WORDING_FREED, | |
168 | WORDING_DELETED, | |
169 | WORDING_DEALLOCATED, | |
170 | WORDING_REALLOCATED | |
171 | }; | |
172 | ||
173 | /* Base class representing a deallocation function, | |
174 | either a built-in one we know about, or one exposed via | |
175 | __attribute__((malloc(DEALLOCATOR))). */ | |
176 | ||
177 | struct deallocator | |
178 | { | |
179 | hashval_t hash () const; | |
180 | void dump_to_pp (pretty_printer *pp) const; | |
181 | static int cmp (const deallocator *a, const deallocator *b); | |
182 | static int cmp_ptr_ptr (const void *, const void *); | |
183 | ||
184 | /* Name to use in diagnostics. */ | |
185 | const char *m_name; | |
186 | ||
187 | /* Which wording to use in diagnostics. */ | |
188 | enum wording m_wording; | |
189 | ||
190 | /* State for a value passed to one of the deallocators. */ | |
191 | state_machine::state_t m_freed; | |
192 | ||
193 | protected: | |
194 | deallocator (malloc_state_machine *sm, | |
195 | const char *name, | |
196 | enum wording wording); | |
197 | }; | |
198 | ||
199 | /* Subclass representing a predefined deallocator. | |
200 | e.g. "delete []", without needing a specific FUNCTION_DECL | |
201 | ahead of time. */ | |
202 | ||
203 | struct standard_deallocator : public deallocator | |
204 | { | |
205 | standard_deallocator (malloc_state_machine *sm, | |
206 | const char *name, | |
207 | enum wording wording); | |
208 | }; | |
209 | ||
210 | /* Subclass representing a user-defined deallocator | |
211 | via __attribute__((malloc(DEALLOCATOR))) given | |
212 | a specific FUNCTION_DECL. */ | |
213 | ||
214 | struct custom_deallocator : public deallocator | |
215 | { | |
216 | custom_deallocator (malloc_state_machine *sm, | |
217 | tree deallocator_fndecl, | |
218 | enum wording wording) | |
219 | : deallocator (sm, IDENTIFIER_POINTER (DECL_NAME (deallocator_fndecl)), | |
220 | wording) | |
221 | { | |
222 | } | |
223 | }; | |
224 | ||
225 | /* Base class representing a set of possible deallocators. | |
226 | Often this will be just a single deallocator, but some | |
227 | allocators have multiple valid deallocators (e.g. the result of | |
228 | "fopen" can be closed by either "fclose" or "freopen"). */ | |
229 | ||
230 | struct deallocator_set | |
231 | { | |
232 | deallocator_set (malloc_state_machine *sm, | |
233 | enum wording wording); | |
234 | virtual ~deallocator_set () {} | |
235 | ||
236 | virtual bool contains_p (const deallocator *d) const = 0; | |
237 | virtual const deallocator *maybe_get_single () const = 0; | |
238 | virtual void dump_to_pp (pretty_printer *pp) const = 0; | |
239 | void dump () const; | |
240 | ||
241 | /* Which wording to use in diagnostics. */ | |
242 | enum wording m_wording; | |
243 | ||
244 | /* Pointers to states. | |
245 | These states are owned by the state_machine base class. */ | |
246 | ||
247 | /* State for an unchecked result from an allocator using this set. */ | |
248 | state_machine::state_t m_unchecked; | |
249 | ||
250 | /* State for a known non-NULL result from such an allocator. */ | |
251 | state_machine::state_t m_nonnull; | |
252 | }; | |
253 | ||
254 | /* Subclass of deallocator_set representing a set of deallocators | |
255 | defined by one or more __attribute__((malloc(DEALLOCATOR))). */ | |
256 | ||
257 | struct custom_deallocator_set : public deallocator_set | |
258 | { | |
259 | typedef const auto_vec <const deallocator *> *key_t; | |
260 | ||
261 | custom_deallocator_set (malloc_state_machine *sm, | |
262 | const auto_vec <const deallocator *> *vec, | |
263 | //const char *name, | |
264 | //const char *dealloc_funcname, | |
265 | //unsigned arg_idx, | |
266 | enum wording wording); | |
267 | ||
268 | bool contains_p (const deallocator *d) const final override; | |
269 | const deallocator *maybe_get_single () const final override; | |
270 | void dump_to_pp (pretty_printer *pp) const final override; | |
271 | ||
272 | auto_vec <const deallocator *> m_deallocator_vec; | |
273 | }; | |
274 | ||
275 | /* Subclass of deallocator_set representing a set of deallocators | |
276 | with a single standard_deallocator, e.g. "delete []". */ | |
277 | ||
278 | struct standard_deallocator_set : public deallocator_set | |
279 | { | |
280 | standard_deallocator_set (malloc_state_machine *sm, | |
281 | const char *name, | |
282 | enum wording wording); | |
283 | ||
284 | bool contains_p (const deallocator *d) const final override; | |
285 | const deallocator *maybe_get_single () const final override; | |
286 | void dump_to_pp (pretty_printer *pp) const final override; | |
287 | ||
288 | standard_deallocator m_deallocator; | |
289 | }; | |
290 | ||
291 | /* Traits class for ensuring uniqueness of deallocator_sets within | |
292 | malloc_state_machine. */ | |
293 | ||
294 | struct deallocator_set_map_traits | |
295 | { | |
296 | typedef custom_deallocator_set::key_t key_type; | |
297 | typedef custom_deallocator_set *value_type; | |
298 | typedef custom_deallocator_set *compare_type; | |
299 | ||
300 | static inline hashval_t hash (const key_type &k) | |
301 | { | |
302 | gcc_assert (k != NULL); | |
303 | gcc_assert (k != reinterpret_cast<key_type> (1)); | |
304 | ||
305 | hashval_t result = 0; | |
306 | unsigned i; | |
307 | const deallocator *d; | |
308 | FOR_EACH_VEC_ELT (*k, i, d) | |
309 | result ^= d->hash (); | |
310 | return result; | |
311 | } | |
312 | static inline bool equal_keys (const key_type &k1, const key_type &k2) | |
313 | { | |
314 | if (k1->length () != k2->length ()) | |
315 | return false; | |
316 | ||
317 | for (unsigned i = 0; i < k1->length (); i++) | |
318 | if ((*k1)[i] != (*k2)[i]) | |
319 | return false; | |
320 | ||
321 | return true; | |
322 | } | |
323 | template <typename T> | |
324 | static inline void remove (T &) | |
325 | { | |
326 | /* empty; the nodes are handled elsewhere. */ | |
327 | } | |
328 | template <typename T> | |
329 | static inline void mark_deleted (T &entry) | |
330 | { | |
331 | entry.m_key = reinterpret_cast<key_type> (1); | |
332 | } | |
333 | template <typename T> | |
334 | static inline void mark_empty (T &entry) | |
335 | { | |
336 | entry.m_key = NULL; | |
337 | } | |
338 | template <typename T> | |
339 | static inline bool is_deleted (const T &entry) | |
340 | { | |
341 | return entry.m_key == reinterpret_cast<key_type> (1); | |
342 | } | |
343 | template <typename T> | |
344 | static inline bool is_empty (const T &entry) | |
345 | { | |
346 | return entry.m_key == NULL; | |
347 | } | |
348 | static const bool empty_zero_p = false; | |
349 | }; | |
350 | ||
351 | /* A state machine for detecting misuses of the malloc/free API. | |
352 | ||
353 | See sm-malloc.dot for an overview (keep this in-sync with that file). */ | |
354 | ||
355 | class malloc_state_machine : public state_machine | |
356 | { | |
357 | public: | |
358 | typedef allocation_state custom_data_t; | |
359 | ||
360 | malloc_state_machine (logger *logger); | |
361 | ~malloc_state_machine (); | |
362 | ||
363 | state_t | |
364 | add_state (const char *name, enum resource_state rs, | |
365 | const deallocator_set *deallocators, | |
366 | const deallocator *deallocator); | |
367 | ||
368 | bool inherited_state_p () const final override { return false; } | |
369 | ||
370 | state_machine::state_t | |
371 | get_default_state (const svalue *sval) const final override | |
372 | { | |
373 | if (tree cst = sval->maybe_get_constant ()) | |
374 | { | |
375 | if (zerop (cst)) | |
376 | return m_null; | |
377 | } | |
378 | if (const region_svalue *ptr = sval->dyn_cast_region_svalue ()) | |
379 | { | |
380 | const region *reg = ptr->get_pointee (); | |
381 | switch (reg->get_memory_space ()) | |
382 | { | |
383 | default: | |
384 | break; | |
385 | case MEMSPACE_CODE: | |
386 | case MEMSPACE_GLOBALS: | |
387 | case MEMSPACE_STACK: | |
388 | case MEMSPACE_READONLY_DATA: | |
389 | return m_non_heap; | |
390 | } | |
391 | } | |
392 | return m_start; | |
393 | } | |
394 | ||
395 | bool on_stmt (sm_context *sm_ctxt, | |
396 | const supernode *node, | |
397 | const gimple *stmt) const final override; | |
398 | ||
399 | void on_phi (sm_context *sm_ctxt, | |
400 | const supernode *node, | |
401 | const gphi *phi, | |
402 | tree rhs) const final override; | |
403 | ||
404 | void on_condition (sm_context *sm_ctxt, | |
405 | const supernode *node, | |
406 | const gimple *stmt, | |
407 | const svalue *lhs, | |
408 | enum tree_code op, | |
409 | const svalue *rhs) const final override; | |
410 | ||
411 | void on_pop_frame (sm_state_map *smap, | |
412 | const frame_region *) const final override; | |
413 | ||
414 | bool can_purge_p (state_t s) const final override; | |
415 | std::unique_ptr<pending_diagnostic> on_leak (tree var) const final override; | |
416 | ||
417 | bool reset_when_passed_to_unknown_fn_p (state_t s, | |
418 | bool is_mutable) const final override; | |
419 | ||
420 | state_t | |
421 | maybe_get_merged_states_nonequal (state_t state_a, | |
422 | state_t state_b) const final override; | |
423 | ||
424 | static bool unaffected_by_call_p (tree fndecl); | |
425 | ||
426 | void maybe_assume_non_null (sm_context *sm_ctxt, | |
427 | tree ptr, | |
428 | const gimple *stmt) const; | |
429 | ||
430 | void on_realloc_with_move (region_model *model, | |
431 | sm_state_map *smap, | |
432 | const svalue *old_ptr_sval, | |
433 | const svalue *new_ptr_sval, | |
434 | const extrinsic_state &ext_state) const; | |
435 | ||
436 | void transition_ptr_sval_non_null (region_model *model, | |
437 | sm_state_map *smap, | |
438 | const svalue *new_ptr_sval, | |
439 | const extrinsic_state &ext_state) const; | |
440 | ||
441 | standard_deallocator_set m_free; | |
442 | standard_deallocator_set m_scalar_delete; | |
443 | standard_deallocator_set m_vector_delete; | |
444 | ||
445 | standard_deallocator m_realloc; | |
446 | ||
447 | /* States that are independent of api. */ | |
448 | ||
449 | /* States for a pointer that's been unconditionally dereferenced | |
450 | in a particular stack frame. */ | |
451 | hash_map<const frame_region *, state_t> m_assumed_non_null; | |
452 | ||
453 | /* State for a pointer that's known to be NULL. */ | |
454 | state_t m_null; | |
455 | ||
456 | /* State for a pointer that's known to not be on the heap (e.g. to a local | |
457 | or global). */ | |
458 | state_t m_non_heap; // TODO: or should this be a different state machine? | |
459 | // or do we need child values etc? | |
460 | ||
461 | /* Stop state, for pointers we don't want to track any more. */ | |
462 | state_t m_stop; | |
463 | ||
464 | private: | |
465 | const custom_deallocator_set * | |
466 | get_or_create_custom_deallocator_set (tree allocator_fndecl); | |
467 | custom_deallocator_set * | |
468 | maybe_create_custom_deallocator_set (tree allocator_fndecl); | |
469 | const deallocator * | |
470 | get_or_create_deallocator (tree deallocator_fndecl); | |
471 | ||
472 | state_t | |
473 | get_or_create_assumed_non_null_state_for_frame (const frame_region *frame); | |
474 | ||
475 | void | |
476 | maybe_complain_about_deref_before_check (sm_context *sm_ctxt, | |
477 | const supernode *node, | |
478 | const gimple *stmt, | |
479 | const assumed_non_null_state *, | |
480 | tree ptr) const; | |
481 | ||
482 | void on_allocator_call (sm_context *sm_ctxt, | |
483 | const gcall *call, | |
484 | const deallocator_set *deallocators, | |
485 | bool returns_nonnull = false) const; | |
486 | void handle_free_of_non_heap (sm_context *sm_ctxt, | |
487 | const supernode *node, | |
488 | const gcall *call, | |
489 | tree arg, | |
490 | const deallocator *d) const; | |
491 | void on_deallocator_call (sm_context *sm_ctxt, | |
492 | const supernode *node, | |
493 | const gcall *call, | |
494 | const deallocator *d, | |
495 | unsigned argno) const; | |
496 | void on_realloc_call (sm_context *sm_ctxt, | |
497 | const supernode *node, | |
498 | const gcall *call) const; | |
499 | void on_zero_assignment (sm_context *sm_ctxt, | |
500 | const gimple *stmt, | |
501 | tree lhs) const; | |
502 | ||
503 | /* A map for consolidating deallocators so that they are | |
504 | unique per deallocator FUNCTION_DECL. */ | |
505 | typedef hash_map<tree, deallocator *> deallocator_map_t; | |
506 | deallocator_map_t m_deallocator_map; | |
507 | ||
508 | /* Memoized lookups from FUNCTION_DECL to custom_deallocator_set *. */ | |
509 | typedef hash_map<tree, custom_deallocator_set *> deallocator_set_cache_t; | |
510 | deallocator_set_cache_t m_custom_deallocator_set_cache; | |
511 | ||
512 | /* A map for consolidating custom_deallocator_set instances. */ | |
513 | typedef hash_map<custom_deallocator_set::key_t, | |
514 | custom_deallocator_set *, | |
515 | deallocator_set_map_traits> custom_deallocator_set_map_t; | |
516 | custom_deallocator_set_map_t m_custom_deallocator_set_map; | |
517 | ||
518 | /* Record of dynamically-allocated objects, for cleanup. */ | |
519 | auto_vec <custom_deallocator_set *> m_dynamic_sets; | |
520 | auto_vec <custom_deallocator *> m_dynamic_deallocators; | |
521 | }; | |
522 | ||
523 | /* struct deallocator. */ | |
524 | ||
525 | deallocator::deallocator (malloc_state_machine *sm, | |
526 | const char *name, | |
527 | enum wording wording) | |
528 | : m_name (name), | |
529 | m_wording (wording), | |
530 | m_freed (sm->add_state ("freed", RS_FREED, NULL, this)) | |
531 | { | |
532 | } | |
533 | ||
534 | hashval_t | |
535 | deallocator::hash () const | |
536 | { | |
537 | return (hashval_t)m_freed->get_id (); | |
538 | } | |
539 | ||
540 | void | |
541 | deallocator::dump_to_pp (pretty_printer *pp) const | |
542 | { | |
543 | pp_printf (pp, "%qs", m_name); | |
544 | } | |
545 | ||
546 | int | |
547 | deallocator::cmp (const deallocator *a, const deallocator *b) | |
548 | { | |
549 | return (int)a->m_freed->get_id () - (int)b->m_freed->get_id (); | |
550 | } | |
551 | ||
552 | int | |
553 | deallocator::cmp_ptr_ptr (const void *a, const void *b) | |
554 | { | |
555 | return cmp (*(const deallocator * const *)a, | |
556 | *(const deallocator * const *)b); | |
557 | } | |
558 | ||
559 | ||
560 | /* struct standard_deallocator : public deallocator. */ | |
561 | ||
562 | standard_deallocator::standard_deallocator (malloc_state_machine *sm, | |
563 | const char *name, | |
564 | enum wording wording) | |
565 | : deallocator (sm, name, wording) | |
566 | { | |
567 | } | |
568 | ||
569 | /* struct deallocator_set. */ | |
570 | ||
571 | deallocator_set::deallocator_set (malloc_state_machine *sm, | |
572 | enum wording wording) | |
573 | : m_wording (wording), | |
574 | m_unchecked (sm->add_state ("unchecked", RS_UNCHECKED, this, NULL)), | |
575 | m_nonnull (sm->add_state ("nonnull", RS_NONNULL, this, NULL)) | |
576 | { | |
577 | } | |
578 | ||
579 | /* Dump a description of this deallocator_set to stderr. */ | |
580 | ||
581 | DEBUG_FUNCTION void | |
582 | deallocator_set::dump () const | |
583 | { | |
584 | pretty_printer pp; | |
585 | pp_show_color (&pp) = pp_show_color (global_dc->printer); | |
586 | pp.buffer->stream = stderr; | |
587 | dump_to_pp (&pp); | |
588 | pp_newline (&pp); | |
589 | pp_flush (&pp); | |
590 | } | |
591 | ||
592 | /* struct custom_deallocator_set : public deallocator_set. */ | |
593 | ||
594 | custom_deallocator_set:: | |
595 | custom_deallocator_set (malloc_state_machine *sm, | |
596 | const auto_vec <const deallocator *> *vec, | |
597 | enum wording wording) | |
598 | : deallocator_set (sm, wording), | |
599 | m_deallocator_vec (vec->length ()) | |
600 | { | |
601 | unsigned i; | |
602 | const deallocator *d; | |
603 | FOR_EACH_VEC_ELT (*vec, i, d) | |
604 | m_deallocator_vec.safe_push (d); | |
605 | } | |
606 | ||
607 | bool | |
608 | custom_deallocator_set::contains_p (const deallocator *d) const | |
609 | { | |
610 | unsigned i; | |
611 | const deallocator *cd; | |
612 | FOR_EACH_VEC_ELT (m_deallocator_vec, i, cd) | |
613 | if (cd == d) | |
614 | return true; | |
615 | return false; | |
616 | } | |
617 | ||
618 | const deallocator * | |
619 | custom_deallocator_set::maybe_get_single () const | |
620 | { | |
621 | if (m_deallocator_vec.length () == 1) | |
622 | return m_deallocator_vec[0]; | |
623 | return NULL; | |
624 | } | |
625 | ||
626 | void | |
627 | custom_deallocator_set::dump_to_pp (pretty_printer *pp) const | |
628 | { | |
629 | pp_character (pp, '{'); | |
630 | unsigned i; | |
631 | const deallocator *d; | |
632 | FOR_EACH_VEC_ELT (m_deallocator_vec, i, d) | |
633 | { | |
634 | if (i > 0) | |
635 | pp_string (pp, ", "); | |
636 | d->dump_to_pp (pp); | |
637 | } | |
638 | pp_character (pp, '}'); | |
639 | } | |
640 | ||
641 | /* struct standard_deallocator_set : public deallocator_set. */ | |
642 | ||
643 | standard_deallocator_set::standard_deallocator_set (malloc_state_machine *sm, | |
644 | const char *name, | |
645 | enum wording wording) | |
646 | : deallocator_set (sm, wording), | |
647 | m_deallocator (sm, name, wording) | |
648 | { | |
649 | } | |
650 | ||
651 | bool | |
652 | standard_deallocator_set::contains_p (const deallocator *d) const | |
653 | { | |
654 | return d == &m_deallocator; | |
655 | } | |
656 | ||
657 | const deallocator * | |
658 | standard_deallocator_set::maybe_get_single () const | |
659 | { | |
660 | return &m_deallocator; | |
661 | } | |
662 | ||
663 | void | |
664 | standard_deallocator_set::dump_to_pp (pretty_printer *pp) const | |
665 | { | |
666 | pp_character (pp, '{'); | |
667 | pp_string (pp, m_deallocator.m_name); | |
668 | pp_character (pp, '}'); | |
669 | } | |
670 | ||
671 | /* Return STATE cast to the custom state subclass, or NULL for the start state. | |
672 | Everything should be an allocation_state apart from the start state. */ | |
673 | ||
674 | static const allocation_state * | |
675 | dyn_cast_allocation_state (state_machine::state_t state) | |
676 | { | |
677 | if (state->get_id () == 0) | |
678 | return NULL; | |
679 | return static_cast <const allocation_state *> (state); | |
680 | } | |
681 | ||
682 | /* Return STATE cast to the custom state subclass, for a state that is | |
683 | already known to not be the start state . */ | |
684 | ||
685 | static const allocation_state * | |
686 | as_a_allocation_state (state_machine::state_t state) | |
687 | { | |
688 | gcc_assert (state->get_id () != 0); | |
689 | return static_cast <const allocation_state *> (state); | |
690 | } | |
691 | ||
692 | /* Get the resource_state for STATE. */ | |
693 | ||
694 | static enum resource_state | |
695 | get_rs (state_machine::state_t state) | |
696 | { | |
697 | if (const allocation_state *astate = dyn_cast_allocation_state (state)) | |
698 | return astate->m_rs; | |
699 | else | |
700 | return RS_START; | |
701 | } | |
702 | ||
703 | /* Return true if STATE is the start state. */ | |
704 | ||
705 | static bool | |
706 | start_p (state_machine::state_t state) | |
707 | { | |
708 | return get_rs (state) == RS_START; | |
709 | } | |
710 | ||
711 | /* Return true if STATE is an unchecked result from an allocator. */ | |
712 | ||
713 | static bool | |
714 | unchecked_p (state_machine::state_t state) | |
715 | { | |
716 | return get_rs (state) == RS_UNCHECKED; | |
717 | } | |
718 | ||
719 | /* Return true if STATE is a non-null result from an allocator. */ | |
720 | ||
721 | static bool | |
722 | nonnull_p (state_machine::state_t state) | |
723 | { | |
724 | return get_rs (state) == RS_NONNULL; | |
725 | } | |
726 | ||
727 | /* Return true if STATE is a value that has been passed to a deallocator. */ | |
728 | ||
729 | static bool | |
730 | freed_p (state_machine::state_t state) | |
731 | { | |
732 | return get_rs (state) == RS_FREED; | |
733 | } | |
734 | ||
735 | /* Return true if STATE is a value that has been assumed to be non-NULL. */ | |
736 | ||
737 | static bool | |
738 | assumed_non_null_p (state_machine::state_t state) | |
739 | { | |
740 | return get_rs (state) == RS_ASSUMED_NON_NULL; | |
741 | } | |
742 | ||
743 | /* Class for diagnostics relating to malloc_state_machine. */ | |
744 | ||
745 | class malloc_diagnostic : public pending_diagnostic | |
746 | { | |
747 | public: | |
748 | malloc_diagnostic (const malloc_state_machine &sm, tree arg) | |
749 | : m_sm (sm), m_arg (arg) | |
750 | {} | |
751 | ||
752 | bool subclass_equal_p (const pending_diagnostic &base_other) const override | |
753 | { | |
754 | return same_tree_p (m_arg, ((const malloc_diagnostic &)base_other).m_arg); | |
755 | } | |
756 | ||
757 | label_text describe_state_change (const evdesc::state_change &change) | |
758 | override | |
759 | { | |
760 | if (change.m_old_state == m_sm.get_start_state () | |
761 | && (unchecked_p (change.m_new_state) || nonnull_p (change.m_new_state))) | |
762 | // TODO: verify that it's the allocation stmt, not a copy | |
763 | return label_text::borrow ("allocated here"); | |
764 | if (unchecked_p (change.m_old_state) | |
765 | && nonnull_p (change.m_new_state)) | |
766 | { | |
767 | if (change.m_expr) | |
768 | return change.formatted_print ("assuming %qE is non-NULL", | |
769 | change.m_expr); | |
770 | else | |
771 | return change.formatted_print ("assuming %qs is non-NULL", | |
772 | "<unknown>"); | |
773 | } | |
774 | if (change.m_new_state == m_sm.m_null) | |
775 | { | |
776 | if (unchecked_p (change.m_old_state)) | |
777 | { | |
778 | if (change.m_expr) | |
779 | return change.formatted_print ("assuming %qE is NULL", | |
780 | change.m_expr); | |
781 | else | |
782 | return change.formatted_print ("assuming %qs is NULL", | |
783 | "<unknown>"); | |
784 | } | |
785 | else | |
786 | { | |
787 | if (change.m_expr) | |
788 | return change.formatted_print ("%qE is NULL", | |
789 | change.m_expr); | |
790 | else | |
791 | return change.formatted_print ("%qs is NULL", | |
792 | "<unknown>"); | |
793 | } | |
794 | } | |
795 | ||
796 | return label_text (); | |
797 | } | |
798 | ||
799 | diagnostic_event::meaning | |
800 | get_meaning_for_state_change (const evdesc::state_change &change) | |
801 | const final override | |
802 | { | |
803 | if (change.m_old_state == m_sm.get_start_state () | |
804 | && unchecked_p (change.m_new_state)) | |
805 | return diagnostic_event::meaning (diagnostic_event::VERB_acquire, | |
806 | diagnostic_event::NOUN_memory); | |
807 | if (freed_p (change.m_new_state)) | |
808 | return diagnostic_event::meaning (diagnostic_event::VERB_release, | |
809 | diagnostic_event::NOUN_memory); | |
810 | return diagnostic_event::meaning (); | |
811 | } | |
812 | ||
813 | protected: | |
814 | const malloc_state_machine &m_sm; | |
815 | tree m_arg; | |
816 | }; | |
817 | ||
818 | /* Concrete subclass for reporting mismatching allocator/deallocator | |
819 | diagnostics. */ | |
820 | ||
821 | class mismatching_deallocation : public malloc_diagnostic | |
822 | { | |
823 | public: | |
824 | mismatching_deallocation (const malloc_state_machine &sm, tree arg, | |
825 | const deallocator_set *expected_deallocators, | |
826 | const deallocator *actual_dealloc) | |
827 | : malloc_diagnostic (sm, arg), | |
828 | m_expected_deallocators (expected_deallocators), | |
829 | m_actual_dealloc (actual_dealloc) | |
830 | {} | |
831 | ||
832 | const char *get_kind () const final override | |
833 | { | |
834 | return "mismatching_deallocation"; | |
835 | } | |
836 | ||
837 | int get_controlling_option () const final override | |
838 | { | |
839 | return OPT_Wanalyzer_mismatching_deallocation; | |
840 | } | |
841 | ||
842 | bool emit (diagnostic_emission_context &ctxt) final override | |
843 | { | |
844 | auto_diagnostic_group d; | |
845 | ctxt.add_cwe (762); /* CWE-762: Mismatched Memory Management Routines. */ | |
846 | if (const deallocator *expected_dealloc | |
847 | = m_expected_deallocators->maybe_get_single ()) | |
848 | return ctxt.warn ("%qE should have been deallocated with %qs" | |
849 | " but was deallocated with %qs", | |
850 | m_arg, expected_dealloc->m_name, | |
851 | m_actual_dealloc->m_name); | |
852 | else | |
853 | return ctxt.warn ("%qs called on %qE returned from a mismatched" | |
854 | " allocation function", | |
855 | m_actual_dealloc->m_name, m_arg); | |
856 | } | |
857 | ||
858 | label_text describe_state_change (const evdesc::state_change &change) | |
859 | final override | |
860 | { | |
861 | if (unchecked_p (change.m_new_state)) | |
862 | { | |
863 | m_alloc_event = change.m_event_id; | |
864 | if (const deallocator *expected_dealloc | |
865 | = m_expected_deallocators->maybe_get_single ()) | |
866 | return change.formatted_print ("allocated here" | |
867 | " (expects deallocation with %qs)", | |
868 | expected_dealloc->m_name); | |
869 | else | |
870 | return change.formatted_print ("allocated here"); | |
871 | } | |
872 | return malloc_diagnostic::describe_state_change (change); | |
873 | } | |
874 | ||
875 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
876 | { | |
877 | if (m_alloc_event.known_p ()) | |
878 | { | |
879 | if (const deallocator *expected_dealloc | |
880 | = m_expected_deallocators->maybe_get_single ()) | |
881 | return ev.formatted_print | |
882 | ("deallocated with %qs here;" | |
883 | " allocation at %@ expects deallocation with %qs", | |
884 | m_actual_dealloc->m_name, &m_alloc_event, | |
885 | expected_dealloc->m_name); | |
886 | else | |
887 | return ev.formatted_print | |
888 | ("deallocated with %qs here;" | |
889 | " allocated at %@", | |
890 | m_actual_dealloc->m_name, &m_alloc_event); | |
891 | } | |
892 | return ev.formatted_print ("deallocated with %qs here", | |
893 | m_actual_dealloc->m_name); | |
894 | } | |
895 | ||
896 | private: | |
897 | diagnostic_event_id_t m_alloc_event; | |
898 | const deallocator_set *m_expected_deallocators; | |
899 | const deallocator *m_actual_dealloc; | |
900 | }; | |
901 | ||
902 | /* Concrete subclass for reporting double-free diagnostics. */ | |
903 | ||
904 | class double_free : public malloc_diagnostic | |
905 | { | |
906 | public: | |
907 | double_free (const malloc_state_machine &sm, tree arg, const char *funcname) | |
908 | : malloc_diagnostic (sm, arg), m_funcname (funcname) | |
909 | {} | |
910 | ||
911 | const char *get_kind () const final override { return "double_free"; } | |
912 | ||
913 | int get_controlling_option () const final override | |
914 | { | |
915 | return OPT_Wanalyzer_double_free; | |
916 | } | |
917 | ||
918 | bool emit (diagnostic_emission_context &ctxt) final override | |
919 | { | |
920 | auto_diagnostic_group d; | |
921 | ctxt.add_cwe (415); /* CWE-415: Double Free. */ | |
922 | return ctxt.warn ("double-%qs of %qE", m_funcname, m_arg); | |
923 | } | |
924 | ||
925 | label_text describe_state_change (const evdesc::state_change &change) | |
926 | final override | |
927 | { | |
928 | if (freed_p (change.m_new_state)) | |
929 | { | |
930 | m_first_free_event = change.m_event_id; | |
931 | return change.formatted_print ("first %qs here", m_funcname); | |
932 | } | |
933 | return malloc_diagnostic::describe_state_change (change); | |
934 | } | |
935 | ||
936 | label_text describe_call_with_state (const evdesc::call_with_state &info) | |
937 | final override | |
938 | { | |
939 | if (freed_p (info.m_state)) | |
940 | return info.formatted_print | |
941 | ("passing freed pointer %qE in call to %qE from %qE", | |
942 | info.m_expr, info.m_callee_fndecl, info.m_caller_fndecl); | |
943 | return label_text (); | |
944 | } | |
945 | ||
946 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
947 | { | |
948 | if (m_first_free_event.known_p ()) | |
949 | return ev.formatted_print ("second %qs here; first %qs was at %@", | |
950 | m_funcname, m_funcname, | |
951 | &m_first_free_event); | |
952 | return ev.formatted_print ("second %qs here", m_funcname); | |
953 | } | |
954 | ||
955 | private: | |
956 | diagnostic_event_id_t m_first_free_event; | |
957 | const char *m_funcname; | |
958 | }; | |
959 | ||
960 | /* Abstract subclass for describing possible bad uses of NULL. | |
961 | Responsible for describing the call that could return NULL. */ | |
962 | ||
963 | class possible_null : public malloc_diagnostic | |
964 | { | |
965 | public: | |
966 | possible_null (const malloc_state_machine &sm, tree arg) | |
967 | : malloc_diagnostic (sm, arg) | |
968 | {} | |
969 | ||
970 | label_text describe_state_change (const evdesc::state_change &change) | |
971 | final override | |
972 | { | |
973 | if (change.m_old_state == m_sm.get_start_state () | |
974 | && unchecked_p (change.m_new_state)) | |
975 | { | |
976 | m_origin_of_unchecked_event = change.m_event_id; | |
977 | return label_text::borrow ("this call could return NULL"); | |
978 | } | |
979 | return malloc_diagnostic::describe_state_change (change); | |
980 | } | |
981 | ||
982 | label_text describe_return_of_state (const evdesc::return_of_state &info) | |
983 | final override | |
984 | { | |
985 | if (unchecked_p (info.m_state)) | |
986 | return info.formatted_print ("possible return of NULL to %qE from %qE", | |
987 | info.m_caller_fndecl, info.m_callee_fndecl); | |
988 | return label_text (); | |
989 | } | |
990 | ||
991 | protected: | |
992 | diagnostic_event_id_t m_origin_of_unchecked_event; | |
993 | }; | |
994 | ||
995 | /* Concrete subclass for describing dereference of a possible NULL | |
996 | value. */ | |
997 | ||
998 | class possible_null_deref : public possible_null | |
999 | { | |
1000 | public: | |
1001 | possible_null_deref (const malloc_state_machine &sm, tree arg) | |
1002 | : possible_null (sm, arg) | |
1003 | {} | |
1004 | ||
1005 | const char *get_kind () const final override { return "possible_null_deref"; } | |
1006 | ||
1007 | int get_controlling_option () const final override | |
1008 | { | |
1009 | return OPT_Wanalyzer_possible_null_dereference; | |
1010 | } | |
1011 | ||
1012 | bool emit (diagnostic_emission_context &ctxt) final override | |
1013 | { | |
1014 | /* CWE-690: Unchecked Return Value to NULL Pointer Dereference. */ | |
1015 | ctxt.add_cwe (690); | |
1016 | return ctxt.warn ("dereference of possibly-NULL %qE", m_arg); | |
1017 | } | |
1018 | ||
1019 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
1020 | { | |
1021 | if (m_origin_of_unchecked_event.known_p ()) | |
1022 | return ev.formatted_print ("%qE could be NULL: unchecked value from %@", | |
1023 | ev.m_expr, | |
1024 | &m_origin_of_unchecked_event); | |
1025 | else | |
1026 | return ev.formatted_print ("%qE could be NULL", ev.m_expr); | |
1027 | } | |
1028 | ||
1029 | }; | |
1030 | ||
1031 | /* Return true if FNDECL is a C++ method. */ | |
1032 | ||
1033 | static bool | |
1034 | method_p (tree fndecl) | |
1035 | { | |
1036 | return TREE_CODE (TREE_TYPE (fndecl)) == METHOD_TYPE; | |
1037 | } | |
1038 | ||
1039 | /* Return a 1-based description of ARG_IDX (0-based) of FNDECL. | |
1040 | Compare with %P in the C++ FE (implemented in cp/error.cc: parm_to_string | |
1041 | as called from cp_printer). */ | |
1042 | ||
1043 | static label_text | |
1044 | describe_argument_index (tree fndecl, int arg_idx) | |
1045 | { | |
1046 | if (method_p (fndecl)) | |
1047 | if (arg_idx == 0) | |
1048 | return label_text::borrow ("'this'"); | |
1049 | pretty_printer pp; | |
1050 | pp_printf (&pp, "%u", arg_idx + 1 - method_p (fndecl)); | |
1051 | return label_text::take (xstrdup (pp_formatted_text (&pp))); | |
1052 | } | |
1053 | ||
1054 | /* Subroutine for use by possible_null_arg::emit and null_arg::emit. | |
1055 | Issue a note informing that the pertinent argument must be non-NULL. */ | |
1056 | ||
1057 | static void | |
1058 | inform_nonnull_attribute (tree fndecl, int arg_idx) | |
1059 | { | |
1060 | label_text arg_desc = describe_argument_index (fndecl, arg_idx); | |
1061 | inform (DECL_SOURCE_LOCATION (fndecl), | |
1062 | "argument %s of %qD must be non-null", | |
1063 | arg_desc.get (), fndecl); | |
1064 | /* Ideally we would use the location of the parm and underline the | |
1065 | attribute also - but we don't have the location_t values at this point | |
1066 | in the middle-end. | |
1067 | For reference, the C and C++ FEs have get_fndecl_argument_location. */ | |
1068 | } | |
1069 | ||
1070 | /* Concrete subclass for describing passing a possibly-NULL value to a | |
1071 | function marked with __attribute__((nonnull)). */ | |
1072 | ||
1073 | class possible_null_arg : public possible_null | |
1074 | { | |
1075 | public: | |
1076 | possible_null_arg (const malloc_state_machine &sm, tree arg, | |
1077 | tree fndecl, int arg_idx) | |
1078 | : possible_null (sm, arg), | |
1079 | m_fndecl (fndecl), m_arg_idx (arg_idx) | |
1080 | {} | |
1081 | ||
1082 | const char *get_kind () const final override { return "possible_null_arg"; } | |
1083 | ||
1084 | bool subclass_equal_p (const pending_diagnostic &base_other) | |
1085 | const final override | |
1086 | { | |
1087 | const possible_null_arg &sub_other | |
1088 | = (const possible_null_arg &)base_other; | |
1089 | return (same_tree_p (m_arg, sub_other.m_arg) | |
1090 | && m_fndecl == sub_other.m_fndecl | |
1091 | && m_arg_idx == sub_other.m_arg_idx); | |
1092 | } | |
1093 | ||
1094 | int get_controlling_option () const final override | |
1095 | { | |
1096 | return OPT_Wanalyzer_possible_null_argument; | |
1097 | } | |
1098 | ||
1099 | bool emit (diagnostic_emission_context &ctxt) final override | |
1100 | { | |
1101 | /* CWE-690: Unchecked Return Value to NULL Pointer Dereference. */ | |
1102 | auto_diagnostic_group d; | |
1103 | ctxt.add_cwe (690); | |
1104 | bool warned | |
1105 | = ctxt.warn ("use of possibly-NULL %qE where non-null expected", | |
1106 | m_arg); | |
1107 | if (warned) | |
1108 | inform_nonnull_attribute (m_fndecl, m_arg_idx); | |
1109 | return warned; | |
1110 | } | |
1111 | ||
1112 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
1113 | { | |
1114 | label_text arg_desc = describe_argument_index (m_fndecl, m_arg_idx); | |
1115 | label_text result; | |
1116 | if (m_origin_of_unchecked_event.known_p ()) | |
1117 | result = ev.formatted_print ("argument %s (%qE) from %@ could be NULL" | |
1118 | " where non-null expected", | |
1119 | arg_desc.get (), ev.m_expr, | |
1120 | &m_origin_of_unchecked_event); | |
1121 | else | |
1122 | result = ev.formatted_print ("argument %s (%qE) could be NULL" | |
1123 | " where non-null expected", | |
1124 | arg_desc.get (), ev.m_expr); | |
1125 | return result; | |
1126 | } | |
1127 | ||
1128 | private: | |
1129 | tree m_fndecl; | |
1130 | int m_arg_idx; | |
1131 | }; | |
1132 | ||
1133 | /* Concrete subclass for describing a dereference of a NULL value. */ | |
1134 | ||
1135 | class null_deref : public malloc_diagnostic | |
1136 | { | |
1137 | public: | |
1138 | null_deref (const malloc_state_machine &sm, tree arg) | |
1139 | : malloc_diagnostic (sm, arg) {} | |
1140 | ||
1141 | const char *get_kind () const final override { return "null_deref"; } | |
1142 | ||
1143 | int get_controlling_option () const final override | |
1144 | { | |
1145 | return OPT_Wanalyzer_null_dereference; | |
1146 | } | |
1147 | ||
1148 | bool terminate_path_p () const final override { return true; } | |
1149 | ||
1150 | bool emit (diagnostic_emission_context &ctxt) final override | |
1151 | { | |
1152 | /* CWE-476: NULL Pointer Dereference. */ | |
1153 | ctxt.add_cwe (476); | |
1154 | return ctxt.warn ("dereference of NULL %qE", m_arg); | |
1155 | } | |
1156 | ||
1157 | label_text describe_return_of_state (const evdesc::return_of_state &info) | |
1158 | final override | |
1159 | { | |
1160 | if (info.m_state == m_sm.m_null) | |
1161 | return info.formatted_print ("return of NULL to %qE from %qE", | |
1162 | info.m_caller_fndecl, info.m_callee_fndecl); | |
1163 | return label_text (); | |
1164 | } | |
1165 | ||
1166 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
1167 | { | |
1168 | return ev.formatted_print ("dereference of NULL %qE", ev.m_expr); | |
1169 | } | |
1170 | ||
1171 | /* Implementation of pending_diagnostic::supercedes_p for | |
1172 | null-deref. | |
1173 | ||
1174 | We want null-deref to supercede use-of-unitialized-value, | |
1175 | so that if we have these at the same stmt, we don't emit | |
1176 | a use-of-uninitialized, just the null-deref. */ | |
1177 | ||
1178 | bool supercedes_p (const pending_diagnostic &other) const final override | |
1179 | { | |
1180 | if (other.use_of_uninit_p ()) | |
1181 | return true; | |
1182 | ||
1183 | return false; | |
1184 | } | |
1185 | }; | |
1186 | ||
1187 | /* Concrete subclass for describing passing a NULL value to a | |
1188 | function marked with __attribute__((nonnull)). */ | |
1189 | ||
1190 | class null_arg : public malloc_diagnostic | |
1191 | { | |
1192 | public: | |
1193 | null_arg (const malloc_state_machine &sm, tree arg, | |
1194 | tree fndecl, int arg_idx) | |
1195 | : malloc_diagnostic (sm, arg), | |
1196 | m_fndecl (fndecl), m_arg_idx (arg_idx) | |
1197 | {} | |
1198 | ||
1199 | const char *get_kind () const final override { return "null_arg"; } | |
1200 | ||
1201 | bool subclass_equal_p (const pending_diagnostic &base_other) | |
1202 | const final override | |
1203 | { | |
1204 | const null_arg &sub_other | |
1205 | = (const null_arg &)base_other; | |
1206 | return (same_tree_p (m_arg, sub_other.m_arg) | |
1207 | && m_fndecl == sub_other.m_fndecl | |
1208 | && m_arg_idx == sub_other.m_arg_idx); | |
1209 | } | |
1210 | ||
1211 | int get_controlling_option () const final override | |
1212 | { | |
1213 | return OPT_Wanalyzer_null_argument; | |
1214 | } | |
1215 | ||
1216 | bool terminate_path_p () const final override { return true; } | |
1217 | ||
1218 | bool emit (diagnostic_emission_context &ctxt) final override | |
1219 | { | |
1220 | /* CWE-476: NULL Pointer Dereference. */ | |
1221 | auto_diagnostic_group d; | |
1222 | ctxt.add_cwe (476); | |
1223 | ||
1224 | bool warned; | |
1225 | if (zerop (m_arg)) | |
1226 | warned = ctxt.warn ("use of NULL where non-null expected"); | |
1227 | else | |
1228 | warned = ctxt.warn ("use of NULL %qE where non-null expected", | |
1229 | m_arg); | |
1230 | if (warned) | |
1231 | inform_nonnull_attribute (m_fndecl, m_arg_idx); | |
1232 | return warned; | |
1233 | } | |
1234 | ||
1235 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
1236 | { | |
1237 | label_text arg_desc = describe_argument_index (m_fndecl, m_arg_idx); | |
1238 | label_text result; | |
1239 | if (zerop (ev.m_expr)) | |
1240 | result = ev.formatted_print ("argument %s NULL where non-null expected", | |
1241 | arg_desc.get ()); | |
1242 | else | |
1243 | result = ev.formatted_print ("argument %s (%qE) NULL" | |
1244 | " where non-null expected", | |
1245 | arg_desc.get (), ev.m_expr); | |
1246 | return result; | |
1247 | } | |
1248 | ||
1249 | private: | |
1250 | tree m_fndecl; | |
1251 | int m_arg_idx; | |
1252 | }; | |
1253 | ||
1254 | class use_after_free : public malloc_diagnostic | |
1255 | { | |
1256 | public: | |
1257 | use_after_free (const malloc_state_machine &sm, tree arg, | |
1258 | const deallocator *deallocator) | |
1259 | : malloc_diagnostic (sm, arg), | |
1260 | m_deallocator (deallocator) | |
1261 | { | |
1262 | gcc_assert (deallocator); | |
1263 | } | |
1264 | ||
1265 | const char *get_kind () const final override { return "use_after_free"; } | |
1266 | ||
1267 | int get_controlling_option () const final override | |
1268 | { | |
1269 | return OPT_Wanalyzer_use_after_free; | |
1270 | } | |
1271 | ||
1272 | bool emit (diagnostic_emission_context &ctxt) final override | |
1273 | { | |
1274 | /* CWE-416: Use After Free. */ | |
1275 | ctxt.add_cwe (416); | |
1276 | return ctxt.warn ("use after %<%s%> of %qE", | |
1277 | m_deallocator->m_name, m_arg); | |
1278 | } | |
1279 | ||
1280 | label_text describe_state_change (const evdesc::state_change &change) | |
1281 | final override | |
1282 | { | |
1283 | if (freed_p (change.m_new_state)) | |
1284 | { | |
1285 | m_free_event = change.m_event_id; | |
1286 | switch (m_deallocator->m_wording) | |
1287 | { | |
1288 | default: | |
1289 | case WORDING_REALLOCATED: | |
1290 | gcc_unreachable (); | |
1291 | case WORDING_FREED: | |
1292 | return label_text::borrow ("freed here"); | |
1293 | case WORDING_DELETED: | |
1294 | return label_text::borrow ("deleted here"); | |
1295 | case WORDING_DEALLOCATED: | |
1296 | return label_text::borrow ("deallocated here"); | |
1297 | } | |
1298 | } | |
1299 | return malloc_diagnostic::describe_state_change (change); | |
1300 | } | |
1301 | ||
1302 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
1303 | { | |
1304 | const char *funcname = m_deallocator->m_name; | |
1305 | if (m_free_event.known_p ()) | |
1306 | switch (m_deallocator->m_wording) | |
1307 | { | |
1308 | default: | |
1309 | case WORDING_REALLOCATED: | |
1310 | gcc_unreachable (); | |
1311 | case WORDING_FREED: | |
1312 | return ev.formatted_print ("use after %<%s%> of %qE; freed at %@", | |
1313 | funcname, ev.m_expr, &m_free_event); | |
1314 | case WORDING_DELETED: | |
1315 | return ev.formatted_print ("use after %<%s%> of %qE; deleted at %@", | |
1316 | funcname, ev.m_expr, &m_free_event); | |
1317 | case WORDING_DEALLOCATED: | |
1318 | return ev.formatted_print ("use after %<%s%> of %qE;" | |
1319 | " deallocated at %@", | |
1320 | funcname, ev.m_expr, &m_free_event); | |
1321 | } | |
1322 | else | |
1323 | return ev.formatted_print ("use after %<%s%> of %qE", | |
1324 | funcname, ev.m_expr); | |
1325 | } | |
1326 | ||
1327 | /* Implementation of pending_diagnostic::supercedes_p for | |
1328 | use_after_free. | |
1329 | ||
1330 | We want use-after-free to supercede use-of-unitialized-value, | |
1331 | so that if we have these at the same stmt, we don't emit | |
1332 | a use-of-uninitialized, just the use-after-free. | |
1333 | (this is because we fully purge information about freed | |
1334 | buffers when we free them to avoid state explosions, so | |
1335 | that if they are accessed after the free, it looks like | |
1336 | they are uninitialized). */ | |
1337 | ||
1338 | bool supercedes_p (const pending_diagnostic &other) const final override | |
1339 | { | |
1340 | if (other.use_of_uninit_p ()) | |
1341 | return true; | |
1342 | ||
1343 | return false; | |
1344 | } | |
1345 | ||
1346 | private: | |
1347 | diagnostic_event_id_t m_free_event; | |
1348 | const deallocator *m_deallocator; | |
1349 | }; | |
1350 | ||
1351 | class malloc_leak : public malloc_diagnostic | |
1352 | { | |
1353 | public: | |
1354 | malloc_leak (const malloc_state_machine &sm, tree arg) | |
1355 | : malloc_diagnostic (sm, arg) {} | |
1356 | ||
1357 | const char *get_kind () const final override { return "malloc_leak"; } | |
1358 | ||
1359 | int get_controlling_option () const final override | |
1360 | { | |
1361 | return OPT_Wanalyzer_malloc_leak; | |
1362 | } | |
1363 | ||
1364 | bool emit (diagnostic_emission_context &ctxt) final override | |
1365 | { | |
1366 | /* "CWE-401: Missing Release of Memory after Effective Lifetime". */ | |
1367 | ctxt.add_cwe (401); | |
1368 | if (m_arg) | |
1369 | return ctxt.warn ("leak of %qE", m_arg); | |
1370 | else | |
1371 | return ctxt.warn ("leak of %qs", "<unknown>"); | |
1372 | } | |
1373 | ||
1374 | label_text describe_state_change (const evdesc::state_change &change) | |
1375 | final override | |
1376 | { | |
1377 | if (unchecked_p (change.m_new_state) | |
1378 | || (start_p (change.m_old_state) && nonnull_p (change.m_new_state))) | |
1379 | { | |
1380 | m_alloc_event = change.m_event_id; | |
1381 | return label_text::borrow ("allocated here"); | |
1382 | } | |
1383 | return malloc_diagnostic::describe_state_change (change); | |
1384 | } | |
1385 | ||
1386 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
1387 | { | |
1388 | if (ev.m_expr) | |
1389 | { | |
1390 | if (m_alloc_event.known_p ()) | |
1391 | return ev.formatted_print ("%qE leaks here; was allocated at %@", | |
1392 | ev.m_expr, &m_alloc_event); | |
1393 | else | |
1394 | return ev.formatted_print ("%qE leaks here", ev.m_expr); | |
1395 | } | |
1396 | else | |
1397 | { | |
1398 | if (m_alloc_event.known_p ()) | |
1399 | return ev.formatted_print ("%qs leaks here; was allocated at %@", | |
1400 | "<unknown>", &m_alloc_event); | |
1401 | else | |
1402 | return ev.formatted_print ("%qs leaks here", "<unknown>"); | |
1403 | } | |
1404 | } | |
1405 | ||
1406 | private: | |
1407 | diagnostic_event_id_t m_alloc_event; | |
1408 | }; | |
1409 | ||
1410 | class free_of_non_heap : public malloc_diagnostic | |
1411 | { | |
1412 | public: | |
1413 | free_of_non_heap (const malloc_state_machine &sm, tree arg, | |
1414 | const region *freed_reg, | |
1415 | const char *funcname) | |
1416 | : malloc_diagnostic (sm, arg), m_freed_reg (freed_reg), m_funcname (funcname) | |
1417 | { | |
1418 | } | |
1419 | ||
1420 | const char *get_kind () const final override { return "free_of_non_heap"; } | |
1421 | ||
1422 | bool subclass_equal_p (const pending_diagnostic &base_other) const | |
1423 | final override | |
1424 | { | |
1425 | const free_of_non_heap &other = (const free_of_non_heap &)base_other; | |
1426 | return (same_tree_p (m_arg, other.m_arg) | |
1427 | && m_freed_reg == other.m_freed_reg); | |
1428 | } | |
1429 | ||
1430 | int get_controlling_option () const final override | |
1431 | { | |
1432 | return OPT_Wanalyzer_free_of_non_heap; | |
1433 | } | |
1434 | ||
1435 | bool emit (diagnostic_emission_context &ctxt) final override | |
1436 | { | |
1437 | auto_diagnostic_group d; | |
1438 | ctxt.add_cwe (590); /* CWE-590: Free of Memory not on the Heap. */ | |
1439 | switch (get_memory_space ()) | |
1440 | { | |
1441 | default: | |
1442 | case MEMSPACE_HEAP: | |
1443 | gcc_unreachable (); | |
1444 | case MEMSPACE_UNKNOWN: | |
1445 | case MEMSPACE_CODE: | |
1446 | case MEMSPACE_GLOBALS: | |
1447 | case MEMSPACE_READONLY_DATA: | |
1448 | return ctxt.warn ("%<%s%> of %qE which points to memory" | |
1449 | " not on the heap", | |
1450 | m_funcname, m_arg); | |
1451 | break; | |
1452 | case MEMSPACE_STACK: | |
1453 | return ctxt.warn ("%<%s%> of %qE which points to memory" | |
1454 | " on the stack", | |
1455 | m_funcname, m_arg); | |
1456 | break; | |
1457 | } | |
1458 | } | |
1459 | ||
1460 | label_text describe_state_change (const evdesc::state_change &) | |
1461 | final override | |
1462 | { | |
1463 | return label_text::borrow ("pointer is from here"); | |
1464 | } | |
1465 | ||
1466 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
1467 | { | |
1468 | return ev.formatted_print ("call to %qs here", m_funcname); | |
1469 | } | |
1470 | ||
1471 | void mark_interesting_stuff (interesting_t *interest) final override | |
1472 | { | |
1473 | if (m_freed_reg) | |
1474 | interest->add_region_creation (m_freed_reg); | |
1475 | } | |
1476 | ||
1477 | private: | |
1478 | enum memory_space get_memory_space () const | |
1479 | { | |
1480 | if (m_freed_reg) | |
1481 | return m_freed_reg->get_memory_space (); | |
1482 | else | |
1483 | return MEMSPACE_UNKNOWN; | |
1484 | } | |
1485 | ||
1486 | const region *m_freed_reg; | |
1487 | const char *m_funcname; | |
1488 | }; | |
1489 | ||
1490 | /* Concrete pending_diagnostic subclass for -Wanalyzer-deref-before-check. */ | |
1491 | ||
1492 | class deref_before_check : public malloc_diagnostic | |
1493 | { | |
1494 | public: | |
1495 | deref_before_check (const malloc_state_machine &sm, tree arg) | |
1496 | : malloc_diagnostic (sm, arg), | |
1497 | m_deref_enode (NULL), | |
1498 | m_deref_expr (NULL), | |
1499 | m_check_enode (NULL) | |
1500 | { | |
1501 | gcc_assert (arg); | |
1502 | } | |
1503 | ||
1504 | const char *get_kind () const final override { return "deref_before_check"; } | |
1505 | ||
1506 | int get_controlling_option () const final override | |
1507 | { | |
1508 | return OPT_Wanalyzer_deref_before_check; | |
1509 | } | |
1510 | ||
1511 | bool emit (diagnostic_emission_context &ctxt) final override | |
1512 | { | |
1513 | /* Don't emit the warning if we can't show where the deref | |
1514 | and the check occur. */ | |
1515 | if (!m_deref_enode) | |
1516 | return false; | |
1517 | if (!m_check_enode) | |
1518 | return false; | |
1519 | /* Only emit the warning for intraprocedural cases. */ | |
1520 | const program_point &deref_point = m_deref_enode->get_point (); | |
1521 | const program_point &check_point = m_check_enode->get_point (); | |
1522 | ||
1523 | if (!program_point::effectively_intraprocedural_p (deref_point, | |
1524 | check_point)) | |
1525 | return false; | |
1526 | ||
1527 | /* Reject the warning if the check occurs within a macro defintion. | |
1528 | This avoids false positives for such code as: | |
1529 | ||
1530 | #define throw_error \ | |
1531 | do { \ | |
1532 | if (p) \ | |
1533 | cleanup (p); \ | |
1534 | return; \ | |
1535 | } while (0) | |
1536 | ||
1537 | if (p->idx >= n) | |
1538 | throw_error (); | |
1539 | ||
1540 | where the usage of "throw_error" implicitly adds a check | |
1541 | on 'p'. | |
1542 | ||
1543 | We do warn when the check is in a macro expansion if we can get | |
1544 | at the location of the condition and it is't part of the | |
1545 | definition, so that we warn for checks such as: | |
1546 | if (words[0][0] == '@') | |
1547 | return; | |
1548 | g_assert(words[0] != NULL); <--- here | |
1549 | Unfortunately we don't have locations for individual gimple | |
1550 | arguments, so in: | |
1551 | g_assert (ptr); | |
1552 | we merely have a gimple_cond | |
1553 | if (p_2(D) == 0B) | |
1554 | with no way of getting at the location of the condition separately | |
1555 | from that of the gimple_cond (where the "if" is within the macro | |
1556 | definition). We reject the warning for such cases. | |
1557 | ||
1558 | We do warn when the *deref* occurs in a macro, since this can be | |
1559 | a source of real bugs; see e.g. PR 77425. */ | |
1560 | location_t check_loc = m_check_enode->get_point ().get_location (); | |
1561 | if (linemap_location_from_macro_definition_p (line_table, check_loc)) | |
1562 | return false; | |
1563 | ||
1564 | /* Reject if m_deref_expr is sufficiently different from m_arg | |
1565 | for cases where the dereference is spelled differently from | |
1566 | the check, which is probably two different ways to get the | |
1567 | same svalue, and thus not worth reporting. */ | |
1568 | if (!m_deref_expr) | |
1569 | return false; | |
1570 | if (!sufficiently_similar_p (m_deref_expr, m_arg)) | |
1571 | return false; | |
1572 | ||
1573 | /* Reject the warning if the deref's BB doesn't dominate that | |
1574 | of the check, so that we don't warn e.g. for shared cleanup | |
1575 | code that checks a pointer for NULL, when that code is sometimes | |
1576 | used before a deref and sometimes after. | |
1577 | Using the dominance code requires setting cfun. */ | |
1578 | auto_cfun sentinel (m_deref_enode->get_function ()); | |
1579 | calculate_dominance_info (CDI_DOMINATORS); | |
1580 | if (!dominated_by_p (CDI_DOMINATORS, | |
1581 | m_check_enode->get_supernode ()->m_bb, | |
1582 | m_deref_enode->get_supernode ()->m_bb)) | |
1583 | return false; | |
1584 | ||
1585 | return ctxt.warn ("check of %qE for NULL after already" | |
1586 | " dereferencing it", | |
1587 | m_arg); | |
1588 | } | |
1589 | ||
1590 | label_text describe_state_change (const evdesc::state_change &change) | |
1591 | final override | |
1592 | { | |
1593 | if (change.m_old_state == m_sm.get_start_state () | |
1594 | && assumed_non_null_p (change.m_new_state)) | |
1595 | { | |
1596 | m_first_deref_event = change.m_event_id; | |
1597 | m_deref_enode = change.m_event.get_exploded_node (); | |
1598 | m_deref_expr = change.m_expr; | |
1599 | return change.formatted_print ("pointer %qE is dereferenced here", | |
1600 | m_arg); | |
1601 | } | |
1602 | return malloc_diagnostic::describe_state_change (change); | |
1603 | } | |
1604 | ||
1605 | label_text describe_final_event (const evdesc::final_event &ev) final override | |
1606 | { | |
1607 | m_check_enode = ev.m_event.get_exploded_node (); | |
1608 | if (m_first_deref_event.known_p ()) | |
1609 | return ev.formatted_print ("pointer %qE is checked for NULL here but" | |
1610 | " it was already dereferenced at %@", | |
1611 | m_arg, &m_first_deref_event); | |
1612 | else | |
1613 | return ev.formatted_print ("pointer %qE is checked for NULL here but" | |
1614 | " it was already dereferenced", | |
1615 | m_arg); | |
1616 | } | |
1617 | ||
1618 | private: | |
1619 | static bool sufficiently_similar_p (tree expr_a, tree expr_b) | |
1620 | { | |
1621 | pretty_printer *pp_a = global_dc->printer->clone (); | |
1622 | pretty_printer *pp_b = global_dc->printer->clone (); | |
1623 | pp_printf (pp_a, "%qE", expr_a); | |
1624 | pp_printf (pp_b, "%qE", expr_b); | |
1625 | bool result = (strcmp (pp_formatted_text (pp_a), pp_formatted_text (pp_b)) | |
1626 | == 0); | |
1627 | delete pp_a; | |
1628 | delete pp_b; | |
1629 | return result; | |
1630 | } | |
1631 | ||
1632 | diagnostic_event_id_t m_first_deref_event; | |
1633 | const exploded_node *m_deref_enode; | |
1634 | tree m_deref_expr; | |
1635 | const exploded_node *m_check_enode; | |
1636 | }; | |
1637 | ||
1638 | /* struct allocation_state : public state_machine::state. */ | |
1639 | ||
1640 | /* Implementation of state_machine::state::dump_to_pp vfunc | |
1641 | for allocation_state: append the API that this allocation is | |
1642 | associated with. */ | |
1643 | ||
1644 | void | |
1645 | allocation_state::dump_to_pp (pretty_printer *pp) const | |
1646 | { | |
1647 | state_machine::state::dump_to_pp (pp); | |
1648 | if (m_deallocators) | |
1649 | { | |
1650 | pp_string (pp, " ("); | |
1651 | m_deallocators->dump_to_pp (pp); | |
1652 | pp_character (pp, ')'); | |
1653 | } | |
1654 | } | |
1655 | ||
1656 | /* Given a allocation_state for a deallocator_set, get the "nonnull" state | |
1657 | for the corresponding allocator(s). */ | |
1658 | ||
1659 | const allocation_state * | |
1660 | allocation_state::get_nonnull () const | |
1661 | { | |
1662 | gcc_assert (m_deallocators); | |
1663 | return as_a_allocation_state (m_deallocators->m_nonnull); | |
1664 | } | |
1665 | ||
1666 | /* struct assumed_non_null_state : public allocation_state. */ | |
1667 | ||
1668 | void | |
1669 | assumed_non_null_state::dump_to_pp (pretty_printer *pp) const | |
1670 | { | |
1671 | allocation_state::dump_to_pp (pp); | |
1672 | pp_string (pp, " (in "); | |
1673 | m_frame->dump_to_pp (pp, true); | |
1674 | pp_character (pp, ')'); | |
1675 | } | |
1676 | ||
1677 | /* malloc_state_machine's ctor. */ | |
1678 | ||
1679 | malloc_state_machine::malloc_state_machine (logger *logger) | |
1680 | : state_machine ("malloc", logger), | |
1681 | m_free (this, "free", WORDING_FREED), | |
1682 | m_scalar_delete (this, "delete", WORDING_DELETED), | |
1683 | m_vector_delete (this, "delete[]", WORDING_DELETED), | |
1684 | m_realloc (this, "realloc", WORDING_REALLOCATED) | |
1685 | { | |
1686 | gcc_assert (m_start->get_id () == 0); | |
1687 | m_null = add_state ("null", RS_FREED, NULL, NULL); | |
1688 | m_non_heap = add_state ("non-heap", RS_NON_HEAP, NULL, NULL); | |
1689 | m_stop = add_state ("stop", RS_STOP, NULL, NULL); | |
1690 | } | |
1691 | ||
1692 | malloc_state_machine::~malloc_state_machine () | |
1693 | { | |
1694 | unsigned i; | |
1695 | custom_deallocator_set *set; | |
1696 | FOR_EACH_VEC_ELT (m_dynamic_sets, i, set) | |
1697 | delete set; | |
1698 | custom_deallocator *d; | |
1699 | FOR_EACH_VEC_ELT (m_dynamic_deallocators, i, d) | |
1700 | delete d; | |
1701 | } | |
1702 | ||
1703 | state_machine::state_t | |
1704 | malloc_state_machine::add_state (const char *name, enum resource_state rs, | |
1705 | const deallocator_set *deallocators, | |
1706 | const deallocator *deallocator) | |
1707 | { | |
1708 | return add_custom_state (new allocation_state (name, alloc_state_id (), | |
1709 | rs, deallocators, | |
1710 | deallocator)); | |
1711 | } | |
1712 | ||
1713 | /* If ALLOCATOR_FNDECL has any "__attribute__((malloc(FOO)))", | |
1714 | return a custom_deallocator_set for them, consolidating them | |
1715 | to ensure uniqueness of the sets. | |
1716 | ||
1717 | Return NULL if it has no such attributes. */ | |
1718 | ||
1719 | const custom_deallocator_set * | |
1720 | malloc_state_machine:: | |
1721 | get_or_create_custom_deallocator_set (tree allocator_fndecl) | |
1722 | { | |
1723 | /* Early rejection of decls without attributes. */ | |
1724 | tree attrs = DECL_ATTRIBUTES (allocator_fndecl); | |
1725 | if (!attrs) | |
1726 | return NULL; | |
1727 | ||
1728 | /* Otherwise, call maybe_create_custom_deallocator_set, | |
1729 | memoizing the result. */ | |
1730 | if (custom_deallocator_set **slot | |
1731 | = m_custom_deallocator_set_cache.get (allocator_fndecl)) | |
1732 | return *slot; | |
1733 | custom_deallocator_set *set | |
1734 | = maybe_create_custom_deallocator_set (allocator_fndecl); | |
1735 | m_custom_deallocator_set_cache.put (allocator_fndecl, set); | |
1736 | return set; | |
1737 | } | |
1738 | ||
1739 | /* Given ALLOCATOR_FNDECL, a FUNCTION_DECL with attributes, | |
1740 | look for any "__attribute__((malloc(FOO)))" and return a | |
1741 | custom_deallocator_set for them, consolidating them | |
1742 | to ensure uniqueness of the sets. | |
1743 | ||
1744 | Return NULL if it has no such attributes. | |
1745 | ||
1746 | Subroutine of get_or_create_custom_deallocator_set which | |
1747 | memoizes the result. */ | |
1748 | ||
1749 | custom_deallocator_set * | |
1750 | malloc_state_machine:: | |
1751 | maybe_create_custom_deallocator_set (tree allocator_fndecl) | |
1752 | { | |
1753 | tree attrs = DECL_ATTRIBUTES (allocator_fndecl); | |
1754 | gcc_assert (attrs); | |
1755 | ||
1756 | /* Look for instances of __attribute__((malloc(FOO))). */ | |
1757 | auto_vec<const deallocator *> deallocator_vec; | |
1758 | for (tree allocs = attrs; | |
1759 | (allocs = lookup_attribute ("malloc", allocs)); | |
1760 | allocs = TREE_CHAIN (allocs)) | |
1761 | { | |
1762 | tree args = TREE_VALUE (allocs); | |
1763 | if (!args) | |
1764 | continue; | |
1765 | if (TREE_VALUE (args)) | |
1766 | { | |
1767 | const deallocator *d | |
1768 | = get_or_create_deallocator (TREE_VALUE (args)); | |
1769 | deallocator_vec.safe_push (d); | |
1770 | } | |
1771 | } | |
1772 | ||
1773 | /* If there weren't any deallocators, bail. */ | |
1774 | if (deallocator_vec.length () == 0) | |
1775 | return NULL; | |
1776 | ||
1777 | /* Consolidate, so that we reuse existing deallocator_set | |
1778 | instances. */ | |
1779 | deallocator_vec.qsort (deallocator::cmp_ptr_ptr); | |
1780 | custom_deallocator_set **slot | |
1781 | = m_custom_deallocator_set_map.get (&deallocator_vec); | |
1782 | if (slot) | |
1783 | return *slot; | |
1784 | custom_deallocator_set *set | |
1785 | = new custom_deallocator_set (this, &deallocator_vec, WORDING_DEALLOCATED); | |
1786 | m_custom_deallocator_set_map.put (&set->m_deallocator_vec, set); | |
1787 | m_dynamic_sets.safe_push (set); | |
1788 | return set; | |
1789 | } | |
1790 | ||
1791 | /* Get the deallocator for DEALLOCATOR_FNDECL, creating it if necessary. */ | |
1792 | ||
1793 | const deallocator * | |
1794 | malloc_state_machine::get_or_create_deallocator (tree deallocator_fndecl) | |
1795 | { | |
1796 | deallocator **slot = m_deallocator_map.get (deallocator_fndecl); | |
1797 | if (slot) | |
1798 | return *slot; | |
1799 | ||
1800 | /* Reuse "free". */ | |
1801 | deallocator *d; | |
1802 | if (is_named_call_p (deallocator_fndecl, "free") | |
1803 | || is_std_named_call_p (deallocator_fndecl, "free") | |
1804 | || is_named_call_p (deallocator_fndecl, "__builtin_free")) | |
1805 | d = &m_free.m_deallocator; | |
1806 | else | |
1807 | { | |
1808 | custom_deallocator *cd | |
1809 | = new custom_deallocator (this, deallocator_fndecl, | |
1810 | WORDING_DEALLOCATED); | |
1811 | m_dynamic_deallocators.safe_push (cd); | |
1812 | d = cd; | |
1813 | } | |
1814 | m_deallocator_map.put (deallocator_fndecl, d); | |
1815 | return d; | |
1816 | } | |
1817 | ||
1818 | /* Get the "assumed-non-null" state for assumptions made within FRAME, | |
1819 | creating it if necessary. */ | |
1820 | ||
1821 | state_machine::state_t | |
1822 | malloc_state_machine:: | |
1823 | get_or_create_assumed_non_null_state_for_frame (const frame_region *frame) | |
1824 | { | |
1825 | if (state_t *slot = m_assumed_non_null.get (frame)) | |
1826 | return *slot; | |
1827 | state_machine::state *new_state | |
1828 | = new assumed_non_null_state ("assumed-non-null", alloc_state_id (), frame); | |
1829 | add_custom_state (new_state); | |
1830 | m_assumed_non_null.put (frame, new_state); | |
1831 | return new_state; | |
1832 | } | |
1833 | ||
1834 | /* Try to identify the function declaration either by name or as a known malloc | |
1835 | builtin. */ | |
1836 | ||
1837 | static bool | |
1838 | known_allocator_p (const_tree fndecl, const gcall *call) | |
1839 | { | |
1840 | /* Either it is a function we know by name and number of arguments... */ | |
1841 | if (is_named_call_p (fndecl, "malloc", call, 1) | |
1842 | || is_named_call_p (fndecl, "calloc", call, 2) | |
1843 | || is_std_named_call_p (fndecl, "malloc", call, 1) | |
1844 | || is_std_named_call_p (fndecl, "calloc", call, 2) | |
1845 | || is_named_call_p (fndecl, "strdup", call, 1) | |
1846 | || is_named_call_p (fndecl, "strndup", call, 2)) | |
1847 | return true; | |
1848 | ||
1849 | /* ... or it is a builtin allocator that allocates objects freed with | |
1850 | __builtin_free. */ | |
1851 | if (fndecl_built_in_p (fndecl, BUILT_IN_NORMAL)) | |
1852 | switch (DECL_FUNCTION_CODE (fndecl)) | |
1853 | { | |
1854 | case BUILT_IN_MALLOC: | |
1855 | case BUILT_IN_CALLOC: | |
1856 | case BUILT_IN_STRDUP: | |
1857 | case BUILT_IN_STRNDUP: | |
1858 | return true; | |
1859 | default: | |
1860 | break; | |
1861 | } | |
1862 | ||
1863 | return false; | |
1864 | } | |
1865 | ||
1866 | /* If PTR's nullness is not known, transition it to the "assumed-non-null" | |
1867 | state for the current frame. */ | |
1868 | ||
1869 | void | |
1870 | malloc_state_machine::maybe_assume_non_null (sm_context *sm_ctxt, | |
1871 | tree ptr, | |
1872 | const gimple *stmt) const | |
1873 | { | |
1874 | const region_model *old_model = sm_ctxt->get_old_region_model (); | |
1875 | if (!old_model) | |
1876 | return; | |
1877 | ||
1878 | tree null_ptr_cst = build_int_cst (TREE_TYPE (ptr), 0); | |
1879 | tristate known_non_null | |
1880 | = old_model->eval_condition (ptr, NE_EXPR, null_ptr_cst, NULL); | |
1881 | if (known_non_null.is_unknown ()) | |
1882 | { | |
1883 | /* Cast away const-ness for cache-like operations. */ | |
1884 | malloc_state_machine *mut_this | |
1885 | = const_cast <malloc_state_machine *> (this); | |
1886 | state_t next_state | |
1887 | = mut_this->get_or_create_assumed_non_null_state_for_frame | |
1888 | (old_model->get_current_frame ()); | |
1889 | sm_ctxt->set_next_state (stmt, ptr, next_state); | |
1890 | } | |
1891 | } | |
1892 | ||
1893 | /* Implementation of state_machine::on_stmt vfunc for malloc_state_machine. */ | |
1894 | ||
1895 | bool | |
1896 | malloc_state_machine::on_stmt (sm_context *sm_ctxt, | |
1897 | const supernode *node, | |
1898 | const gimple *stmt) const | |
1899 | { | |
1900 | if (const gcall *call = dyn_cast <const gcall *> (stmt)) | |
1901 | if (tree callee_fndecl = sm_ctxt->get_fndecl_for_call (call)) | |
1902 | { | |
1903 | if (known_allocator_p (callee_fndecl, call)) | |
1904 | { | |
1905 | on_allocator_call (sm_ctxt, call, &m_free); | |
1906 | return true; | |
1907 | } | |
1908 | ||
1909 | if (!is_placement_new_p (call)) | |
1910 | { | |
1911 | bool returns_nonnull = !TREE_NOTHROW (callee_fndecl) | |
1912 | && flag_exceptions; | |
1913 | if (is_named_call_p (callee_fndecl, "operator new")) | |
1914 | on_allocator_call (sm_ctxt, call, | |
1915 | &m_scalar_delete, returns_nonnull); | |
1916 | else if (is_named_call_p (callee_fndecl, "operator new []")) | |
1917 | on_allocator_call (sm_ctxt, call, | |
1918 | &m_vector_delete, returns_nonnull); | |
1919 | } | |
1920 | ||
1921 | if (is_named_call_p (callee_fndecl, "operator delete", call, 1) | |
1922 | || is_named_call_p (callee_fndecl, "operator delete", call, 2)) | |
1923 | { | |
1924 | on_deallocator_call (sm_ctxt, node, call, | |
1925 | &m_scalar_delete.m_deallocator, 0); | |
1926 | return true; | |
1927 | } | |
1928 | else if (is_named_call_p (callee_fndecl, "operator delete []", call, 1)) | |
1929 | { | |
1930 | on_deallocator_call (sm_ctxt, node, call, | |
1931 | &m_vector_delete.m_deallocator, 0); | |
1932 | return true; | |
1933 | } | |
1934 | ||
1935 | if (is_named_call_p (callee_fndecl, "alloca", call, 1) | |
1936 | || is_named_call_p (callee_fndecl, "__builtin_alloca", call, 1)) | |
1937 | { | |
1938 | tree lhs = gimple_call_lhs (call); | |
1939 | if (lhs) | |
1940 | sm_ctxt->on_transition (node, stmt, lhs, m_start, m_non_heap); | |
1941 | return true; | |
1942 | } | |
1943 | ||
1944 | if (is_named_call_p (callee_fndecl, "free", call, 1) | |
1945 | || is_std_named_call_p (callee_fndecl, "free", call, 1) | |
1946 | || is_named_call_p (callee_fndecl, "__builtin_free", call, 1)) | |
1947 | { | |
1948 | on_deallocator_call (sm_ctxt, node, call, | |
1949 | &m_free.m_deallocator, 0); | |
1950 | return true; | |
1951 | } | |
1952 | ||
1953 | if (is_named_call_p (callee_fndecl, "realloc", call, 2) | |
1954 | || is_named_call_p (callee_fndecl, "__builtin_realloc", call, 2)) | |
1955 | { | |
1956 | on_realloc_call (sm_ctxt, node, call); | |
1957 | return true; | |
1958 | } | |
1959 | ||
1960 | if (unaffected_by_call_p (callee_fndecl)) | |
1961 | return true; | |
1962 | ||
1963 | /* Cast away const-ness for cache-like operations. */ | |
1964 | malloc_state_machine *mutable_this | |
1965 | = const_cast <malloc_state_machine *> (this); | |
1966 | ||
1967 | /* Handle interesting attributes of the callee_fndecl, | |
1968 | or prioritize those of the builtin that callee_fndecl is expected | |
1969 | to be. | |
1970 | Might want this to be controlled by a flag. */ | |
1971 | { | |
1972 | tree fndecl = callee_fndecl; | |
1973 | /* If call is recognized as a builtin known_function, use that | |
1974 | builtin's function_decl. */ | |
1975 | if (const region_model *old_model = sm_ctxt->get_old_region_model ()) | |
1976 | if (const builtin_known_function *builtin_kf | |
1977 | = old_model->get_builtin_kf (call)) | |
1978 | fndecl = builtin_kf->builtin_decl (); | |
1979 | ||
1980 | /* Handle "__attribute__((malloc(FOO)))". */ | |
1981 | if (const deallocator_set *deallocators | |
1982 | = mutable_this->get_or_create_custom_deallocator_set | |
1983 | (fndecl)) | |
1984 | { | |
1985 | tree attrs = TYPE_ATTRIBUTES (TREE_TYPE (fndecl)); | |
1986 | bool returns_nonnull | |
1987 | = lookup_attribute ("returns_nonnull", attrs); | |
1988 | on_allocator_call (sm_ctxt, call, deallocators, returns_nonnull); | |
1989 | } | |
1990 | ||
1991 | { | |
1992 | /* Handle "__attribute__((nonnull))". */ | |
1993 | tree fntype = TREE_TYPE (fndecl); | |
1994 | bitmap nonnull_args = get_nonnull_args (fntype); | |
1995 | if (nonnull_args) | |
1996 | { | |
1997 | for (unsigned i = 0; i < gimple_call_num_args (stmt); i++) | |
1998 | { | |
1999 | tree arg = gimple_call_arg (stmt, i); | |
2000 | if (TREE_CODE (TREE_TYPE (arg)) != POINTER_TYPE) | |
2001 | continue; | |
2002 | /* If we have a nonnull-args, and either all pointers, or | |
2003 | just the specified pointers. */ | |
2004 | if (bitmap_empty_p (nonnull_args) | |
2005 | || bitmap_bit_p (nonnull_args, i)) | |
2006 | { | |
2007 | state_t state = sm_ctxt->get_state (stmt, arg); | |
2008 | /* Can't use a switch as the states are non-const. */ | |
2009 | /* Do use the fndecl that caused the warning so that the | |
2010 | misused attributes are printed and the user not | |
2011 | confused. */ | |
2012 | if (unchecked_p (state)) | |
2013 | { | |
2014 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2015 | sm_ctxt->warn (node, stmt, arg, | |
2016 | make_unique<possible_null_arg> | |
2017 | (*this, diag_arg, fndecl, i)); | |
2018 | const allocation_state *astate | |
2019 | = as_a_allocation_state (state); | |
2020 | sm_ctxt->set_next_state (stmt, arg, | |
2021 | astate->get_nonnull ()); | |
2022 | } | |
2023 | else if (state == m_null) | |
2024 | { | |
2025 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2026 | sm_ctxt->warn (node, stmt, arg, | |
2027 | make_unique<null_arg> | |
2028 | (*this, diag_arg, fndecl, i)); | |
2029 | sm_ctxt->set_next_state (stmt, arg, m_stop); | |
2030 | } | |
2031 | else if (state == m_start) | |
2032 | maybe_assume_non_null (sm_ctxt, arg, stmt); | |
2033 | } | |
2034 | } | |
2035 | BITMAP_FREE (nonnull_args); | |
2036 | } | |
2037 | } | |
2038 | ||
2039 | /* Check for this after nonnull, so that if we have both | |
2040 | then we transition to "freed", rather than "checked". */ | |
2041 | unsigned dealloc_argno = fndecl_dealloc_argno (fndecl); | |
2042 | if (dealloc_argno != UINT_MAX) | |
2043 | { | |
2044 | const deallocator *d | |
2045 | = mutable_this->get_or_create_deallocator (fndecl); | |
2046 | on_deallocator_call (sm_ctxt, node, call, d, dealloc_argno); | |
2047 | } | |
2048 | } | |
2049 | } | |
2050 | ||
2051 | /* Look for pointers explicitly being compared against zero | |
2052 | that are in state assumed_non_null i.e. we already defererenced | |
2053 | them. | |
2054 | We have to do this check here, rather than in on_condition | |
2055 | because we add a constraint that the pointer is non-null when | |
2056 | dereferencing it, and this makes the apply_constraints_for_gcond | |
2057 | find known-true and known-false conditions; on_condition is only | |
2058 | called when adding new constraints. */ | |
2059 | if (const gcond *cond_stmt = dyn_cast <const gcond *> (stmt)) | |
2060 | { | |
2061 | enum tree_code op = gimple_cond_code (cond_stmt); | |
2062 | if (op == EQ_EXPR || op == NE_EXPR) | |
2063 | { | |
2064 | tree lhs = gimple_cond_lhs (cond_stmt); | |
2065 | tree rhs = gimple_cond_rhs (cond_stmt); | |
2066 | if (any_pointer_p (lhs) | |
2067 | && any_pointer_p (rhs) | |
2068 | && zerop (rhs)) | |
2069 | { | |
2070 | state_t state = sm_ctxt->get_state (stmt, lhs); | |
2071 | if (assumed_non_null_p (state)) | |
2072 | maybe_complain_about_deref_before_check | |
2073 | (sm_ctxt, node, | |
2074 | stmt, | |
2075 | (const assumed_non_null_state *)state, | |
2076 | lhs); | |
2077 | } | |
2078 | } | |
2079 | } | |
2080 | ||
2081 | if (tree lhs = sm_ctxt->is_zero_assignment (stmt)) | |
2082 | if (any_pointer_p (lhs)) | |
2083 | on_zero_assignment (sm_ctxt, stmt,lhs); | |
2084 | ||
2085 | /* Handle dereferences. */ | |
2086 | for (unsigned i = 0; i < gimple_num_ops (stmt); i++) | |
2087 | { | |
2088 | tree op = gimple_op (stmt, i); | |
2089 | if (!op) | |
2090 | continue; | |
2091 | if (TREE_CODE (op) == COMPONENT_REF) | |
2092 | op = TREE_OPERAND (op, 0); | |
2093 | ||
2094 | if (TREE_CODE (op) == MEM_REF) | |
2095 | { | |
2096 | tree arg = TREE_OPERAND (op, 0); | |
2097 | ||
2098 | state_t state = sm_ctxt->get_state (stmt, arg); | |
2099 | if (state == m_start) | |
2100 | maybe_assume_non_null (sm_ctxt, arg, stmt); | |
2101 | else if (unchecked_p (state)) | |
2102 | { | |
2103 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2104 | sm_ctxt->warn (node, stmt, arg, | |
2105 | make_unique<possible_null_deref> (*this, | |
2106 | diag_arg)); | |
2107 | const allocation_state *astate = as_a_allocation_state (state); | |
2108 | sm_ctxt->set_next_state (stmt, arg, astate->get_nonnull ()); | |
2109 | } | |
2110 | else if (state == m_null) | |
2111 | { | |
2112 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2113 | sm_ctxt->warn (node, stmt, arg, | |
2114 | make_unique<null_deref> (*this, diag_arg)); | |
2115 | sm_ctxt->set_next_state (stmt, arg, m_stop); | |
2116 | } | |
2117 | else if (freed_p (state)) | |
2118 | { | |
2119 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2120 | const allocation_state *astate = as_a_allocation_state (state); | |
2121 | sm_ctxt->warn (node, stmt, arg, | |
2122 | make_unique<use_after_free> | |
2123 | (*this, diag_arg, astate->m_deallocator)); | |
2124 | sm_ctxt->set_next_state (stmt, arg, m_stop); | |
2125 | } | |
2126 | } | |
2127 | } | |
2128 | return false; | |
2129 | } | |
2130 | ||
2131 | /* Given a check against null of PTR in assumed-non-null state STATE, | |
2132 | potentially add a deref_before_check warning to SM_CTXT. */ | |
2133 | ||
2134 | void | |
2135 | malloc_state_machine:: | |
2136 | maybe_complain_about_deref_before_check (sm_context *sm_ctxt, | |
2137 | const supernode *node, | |
2138 | const gimple *stmt, | |
2139 | const assumed_non_null_state *state, | |
2140 | tree ptr) const | |
2141 | { | |
2142 | const region_model *model = sm_ctxt->get_old_region_model (); | |
2143 | if (!model) | |
2144 | return; | |
2145 | ||
2146 | /* Don't complain if the current frame (where the check is occurring) is | |
2147 | deeper than the frame in which the "not null" assumption was made. | |
2148 | This suppress false positives for cases like: | |
2149 | ||
2150 | void foo (struct s *p) | |
2151 | { | |
2152 | int val = s->some_field; // deref here | |
2153 | shared_helper (p); | |
2154 | } | |
2155 | ||
2156 | where "shared_helper" has: | |
2157 | ||
2158 | void shared_helper (struct s *p) | |
2159 | { | |
2160 | if (!p) // check here | |
2161 | return; | |
2162 | // etc | |
2163 | } | |
2164 | ||
2165 | since the check in "shared_helper" is OK. */ | |
2166 | const frame_region *checked_in_frame = model->get_current_frame (); | |
2167 | const frame_region *assumed_nonnull_in_frame = state->m_frame; | |
2168 | if (checked_in_frame->get_index () > assumed_nonnull_in_frame->get_index ()) | |
2169 | return; | |
2170 | ||
2171 | tree diag_ptr = sm_ctxt->get_diagnostic_tree (ptr); | |
2172 | if (diag_ptr) | |
2173 | sm_ctxt->warn | |
2174 | (node, stmt, ptr, | |
2175 | make_unique<deref_before_check> (*this, diag_ptr)); | |
2176 | sm_ctxt->set_next_state (stmt, ptr, m_stop); | |
2177 | } | |
2178 | ||
2179 | /* Handle a call to an allocator. | |
2180 | RETURNS_NONNULL is true if CALL is to a fndecl known to have | |
2181 | __attribute__((returns_nonnull)). */ | |
2182 | ||
2183 | void | |
2184 | malloc_state_machine::on_allocator_call (sm_context *sm_ctxt, | |
2185 | const gcall *call, | |
2186 | const deallocator_set *deallocators, | |
2187 | bool returns_nonnull) const | |
2188 | { | |
2189 | tree lhs = gimple_call_lhs (call); | |
2190 | if (lhs) | |
2191 | { | |
2192 | if (sm_ctxt->get_state (call, lhs) == m_start) | |
2193 | sm_ctxt->set_next_state (call, lhs, | |
2194 | (returns_nonnull | |
2195 | ? deallocators->m_nonnull | |
2196 | : deallocators->m_unchecked)); | |
2197 | } | |
2198 | else | |
2199 | { | |
2200 | /* TODO: report leak. */ | |
2201 | } | |
2202 | } | |
2203 | ||
2204 | /* Handle deallocations of non-heap pointers. | |
2205 | non-heap -> stop, with warning. */ | |
2206 | ||
2207 | void | |
2208 | malloc_state_machine::handle_free_of_non_heap (sm_context *sm_ctxt, | |
2209 | const supernode *node, | |
2210 | const gcall *call, | |
2211 | tree arg, | |
2212 | const deallocator *d) const | |
2213 | { | |
2214 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2215 | const region *freed_reg = NULL; | |
2216 | if (const program_state *old_state = sm_ctxt->get_old_program_state ()) | |
2217 | { | |
2218 | const region_model *old_model = old_state->m_region_model; | |
2219 | const svalue *ptr_sval = old_model->get_rvalue (arg, NULL); | |
2220 | freed_reg = old_model->deref_rvalue (ptr_sval, arg, NULL); | |
2221 | } | |
2222 | sm_ctxt->warn (node, call, arg, | |
2223 | make_unique<free_of_non_heap> | |
2224 | (*this, diag_arg, freed_reg, d->m_name)); | |
2225 | sm_ctxt->set_next_state (call, arg, m_stop); | |
2226 | } | |
2227 | ||
2228 | void | |
2229 | malloc_state_machine::on_deallocator_call (sm_context *sm_ctxt, | |
2230 | const supernode *node, | |
2231 | const gcall *call, | |
2232 | const deallocator *d, | |
2233 | unsigned argno) const | |
2234 | { | |
2235 | if (argno >= gimple_call_num_args (call)) | |
2236 | return; | |
2237 | tree arg = gimple_call_arg (call, argno); | |
2238 | ||
2239 | state_t state = sm_ctxt->get_state (call, arg); | |
2240 | ||
2241 | /* start/assumed_non_null/unchecked/nonnull -> freed. */ | |
2242 | if (state == m_start || assumed_non_null_p (state)) | |
2243 | sm_ctxt->set_next_state (call, arg, d->m_freed); | |
2244 | else if (unchecked_p (state) || nonnull_p (state)) | |
2245 | { | |
2246 | const allocation_state *astate = as_a_allocation_state (state); | |
2247 | gcc_assert (astate->m_deallocators); | |
2248 | if (!astate->m_deallocators->contains_p (d)) | |
2249 | { | |
2250 | /* Wrong allocator. */ | |
2251 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2252 | sm_ctxt->warn (node, call, arg, | |
2253 | make_unique<mismatching_deallocation> | |
2254 | (*this, diag_arg, | |
2255 | astate->m_deallocators, | |
2256 | d)); | |
2257 | } | |
2258 | sm_ctxt->set_next_state (call, arg, d->m_freed); | |
2259 | } | |
2260 | ||
2261 | /* Keep state "null" as-is, rather than transitioning to "freed"; | |
2262 | we don't want to complain about double-free of NULL. */ | |
2263 | else if (state == d->m_freed) | |
2264 | { | |
2265 | /* freed -> stop, with warning. */ | |
2266 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2267 | sm_ctxt->warn (node, call, arg, | |
2268 | make_unique<double_free> (*this, diag_arg, d->m_name)); | |
2269 | sm_ctxt->set_next_state (call, arg, m_stop); | |
2270 | } | |
2271 | else if (state == m_non_heap) | |
2272 | { | |
2273 | /* non-heap -> stop, with warning. */ | |
2274 | handle_free_of_non_heap (sm_ctxt, node, call, arg, d); | |
2275 | } | |
2276 | } | |
2277 | ||
2278 | /* Handle a call to "realloc". | |
2279 | Check for free of non-heap or mismatching allocators, | |
2280 | transitioning to the "stop" state for such cases. | |
2281 | ||
2282 | Otherwise, kf_realloc::impl_call_post will later | |
2283 | get called (which will handle other sm-state transitions | |
2284 | when the state is bifurcated). */ | |
2285 | ||
2286 | void | |
2287 | malloc_state_machine::on_realloc_call (sm_context *sm_ctxt, | |
2288 | const supernode *node, | |
2289 | const gcall *call) const | |
2290 | { | |
2291 | const unsigned argno = 0; | |
2292 | const deallocator *d = &m_realloc; | |
2293 | ||
2294 | tree arg = gimple_call_arg (call, argno); | |
2295 | ||
2296 | state_t state = sm_ctxt->get_state (call, arg); | |
2297 | ||
2298 | if (unchecked_p (state) || nonnull_p (state)) | |
2299 | { | |
2300 | const allocation_state *astate = as_a_allocation_state (state); | |
2301 | gcc_assert (astate->m_deallocators); | |
2302 | if (!astate->m_deallocators->contains_p (&m_free.m_deallocator)) | |
2303 | { | |
2304 | /* Wrong allocator. */ | |
2305 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2306 | sm_ctxt->warn (node, call, arg, | |
2307 | make_unique<mismatching_deallocation> | |
2308 | (*this, diag_arg, | |
2309 | astate->m_deallocators, d)); | |
2310 | sm_ctxt->set_next_state (call, arg, m_stop); | |
2311 | if (path_context *path_ctxt = sm_ctxt->get_path_context ()) | |
2312 | path_ctxt->terminate_path (); | |
2313 | } | |
2314 | } | |
2315 | else if (state == m_free.m_deallocator.m_freed) | |
2316 | { | |
2317 | /* freed -> stop, with warning. */ | |
2318 | tree diag_arg = sm_ctxt->get_diagnostic_tree (arg); | |
2319 | sm_ctxt->warn (node, call, arg, | |
2320 | make_unique<double_free> (*this, diag_arg, "free")); | |
2321 | sm_ctxt->set_next_state (call, arg, m_stop); | |
2322 | if (path_context *path_ctxt = sm_ctxt->get_path_context ()) | |
2323 | path_ctxt->terminate_path (); | |
2324 | } | |
2325 | else if (state == m_non_heap) | |
2326 | { | |
2327 | /* non-heap -> stop, with warning. */ | |
2328 | handle_free_of_non_heap (sm_ctxt, node, call, arg, d); | |
2329 | if (path_context *path_ctxt = sm_ctxt->get_path_context ()) | |
2330 | path_ctxt->terminate_path (); | |
2331 | } | |
2332 | } | |
2333 | ||
2334 | /* Implementation of state_machine::on_phi vfunc for malloc_state_machine. */ | |
2335 | ||
2336 | void | |
2337 | malloc_state_machine::on_phi (sm_context *sm_ctxt, | |
2338 | const supernode *node ATTRIBUTE_UNUSED, | |
2339 | const gphi *phi, | |
2340 | tree rhs) const | |
2341 | { | |
2342 | if (zerop (rhs)) | |
2343 | { | |
2344 | tree lhs = gimple_phi_result (phi); | |
2345 | on_zero_assignment (sm_ctxt, phi, lhs); | |
2346 | } | |
2347 | } | |
2348 | ||
2349 | /* Implementation of state_machine::on_condition vfunc for malloc_state_machine. | |
2350 | Potentially transition state 'unchecked' to 'nonnull' or to 'null'. */ | |
2351 | ||
2352 | void | |
2353 | malloc_state_machine::on_condition (sm_context *sm_ctxt, | |
2354 | const supernode *node ATTRIBUTE_UNUSED, | |
2355 | const gimple *stmt, | |
2356 | const svalue *lhs, | |
2357 | enum tree_code op, | |
2358 | const svalue *rhs) const | |
2359 | { | |
2360 | if (!rhs->all_zeroes_p ()) | |
2361 | return; | |
2362 | ||
2363 | if (!any_pointer_p (lhs)) | |
2364 | return; | |
2365 | if (!any_pointer_p (rhs)) | |
2366 | return; | |
2367 | ||
2368 | if (op == NE_EXPR) | |
2369 | { | |
2370 | log ("got 'ARG != 0' match"); | |
2371 | state_t s = sm_ctxt->get_state (stmt, lhs); | |
2372 | if (unchecked_p (s)) | |
2373 | { | |
2374 | const allocation_state *astate = as_a_allocation_state (s); | |
2375 | sm_ctxt->set_next_state (stmt, lhs, astate->get_nonnull ()); | |
2376 | } | |
2377 | } | |
2378 | else if (op == EQ_EXPR) | |
2379 | { | |
2380 | log ("got 'ARG == 0' match"); | |
2381 | state_t s = sm_ctxt->get_state (stmt, lhs); | |
2382 | if (unchecked_p (s)) | |
2383 | sm_ctxt->set_next_state (stmt, lhs, m_null); | |
2384 | } | |
2385 | } | |
2386 | ||
2387 | /* Implementation of state_machine::on_pop_frame vfunc for malloc_state_machine. | |
2388 | Clear any "assumed-non-null" state where the assumption happened in | |
2389 | FRAME_REG. */ | |
2390 | ||
2391 | void | |
2392 | malloc_state_machine::on_pop_frame (sm_state_map *smap, | |
2393 | const frame_region *frame_reg) const | |
2394 | { | |
2395 | hash_set<const svalue *> svals_to_clear; | |
2396 | for (auto kv : *smap) | |
2397 | { | |
2398 | const svalue *sval = kv.first; | |
2399 | state_t state = kv.second.m_state; | |
2400 | if (assumed_non_null_p (state)) | |
2401 | { | |
2402 | const assumed_non_null_state *assumed_state | |
2403 | = (const assumed_non_null_state *)state; | |
2404 | if (frame_reg == assumed_state->m_frame) | |
2405 | svals_to_clear.add (sval); | |
2406 | } | |
2407 | } | |
2408 | for (auto sval : svals_to_clear) | |
2409 | smap->clear_any_state (sval); | |
2410 | } | |
2411 | ||
2412 | /* Implementation of state_machine::can_purge_p vfunc for malloc_state_machine. | |
2413 | Don't allow purging of pointers in state 'unchecked' or 'nonnull' | |
2414 | (to avoid false leak reports). */ | |
2415 | ||
2416 | bool | |
2417 | malloc_state_machine::can_purge_p (state_t s) const | |
2418 | { | |
2419 | enum resource_state rs = get_rs (s); | |
2420 | return rs != RS_UNCHECKED && rs != RS_NONNULL; | |
2421 | } | |
2422 | ||
2423 | /* Implementation of state_machine::on_leak vfunc for malloc_state_machine | |
2424 | (for complaining about leaks of pointers in state 'unchecked' and | |
2425 | 'nonnull'). */ | |
2426 | ||
2427 | std::unique_ptr<pending_diagnostic> | |
2428 | malloc_state_machine::on_leak (tree var) const | |
2429 | { | |
2430 | return make_unique<malloc_leak> (*this, var); | |
2431 | } | |
2432 | ||
2433 | /* Implementation of state_machine::reset_when_passed_to_unknown_fn_p vfunc | |
2434 | for malloc_state_machine. */ | |
2435 | ||
2436 | bool | |
2437 | malloc_state_machine::reset_when_passed_to_unknown_fn_p (state_t s, | |
2438 | bool is_mutable) const | |
2439 | { | |
2440 | /* An on-stack ptr doesn't stop being stack-allocated when passed to an | |
2441 | unknown fn. */ | |
2442 | if (s == m_non_heap) | |
2443 | return false; | |
2444 | ||
2445 | /* Otherwise, pointers passed as non-const can be freed. */ | |
2446 | return is_mutable; | |
2447 | } | |
2448 | ||
2449 | /* Implementation of state_machine::maybe_get_merged_states_nonequal vfunc | |
2450 | for malloc_state_machine. | |
2451 | ||
2452 | Support discarding "assumed-non-null" states when merging with | |
2453 | start state. */ | |
2454 | ||
2455 | state_machine::state_t | |
2456 | malloc_state_machine::maybe_get_merged_states_nonequal (state_t state_a, | |
2457 | state_t state_b) const | |
2458 | { | |
2459 | if (assumed_non_null_p (state_a) && state_b == m_start) | |
2460 | return m_start; | |
2461 | if (state_a == m_start && assumed_non_null_p (state_b)) | |
2462 | return m_start; | |
2463 | return NULL; | |
2464 | } | |
2465 | ||
2466 | /* Return true if calls to FNDECL are known to not affect this sm-state. */ | |
2467 | ||
2468 | bool | |
2469 | malloc_state_machine::unaffected_by_call_p (tree fndecl) | |
2470 | { | |
2471 | /* A set of functions that are known to not affect allocation | |
2472 | status, even if we haven't fully modelled the rest of their | |
2473 | behavior yet. */ | |
2474 | static const char * const funcnames[] = { | |
2475 | /* This array must be kept sorted. */ | |
2476 | "strsep", | |
2477 | }; | |
2478 | const size_t count = ARRAY_SIZE (funcnames); | |
2479 | function_set fs (funcnames, count); | |
2480 | ||
2481 | if (fs.contains_decl_p (fndecl)) | |
2482 | return true; | |
2483 | ||
2484 | return false; | |
2485 | } | |
2486 | ||
2487 | /* Shared logic for handling GIMPLE_ASSIGNs and GIMPLE_PHIs that | |
2488 | assign zero to LHS. */ | |
2489 | ||
2490 | void | |
2491 | malloc_state_machine::on_zero_assignment (sm_context *sm_ctxt, | |
2492 | const gimple *stmt, | |
2493 | tree lhs) const | |
2494 | { | |
2495 | state_t s = sm_ctxt->get_state (stmt, lhs); | |
2496 | enum resource_state rs = get_rs (s); | |
2497 | if (rs == RS_START | |
2498 | || rs == RS_UNCHECKED | |
2499 | || rs == RS_NONNULL | |
2500 | || rs == RS_FREED) | |
2501 | sm_ctxt->set_next_state (stmt, lhs, m_null); | |
2502 | } | |
2503 | ||
2504 | /* Special-case hook for handling realloc, for the "success with move to | |
2505 | a new buffer" case, marking OLD_PTR_SVAL as freed and NEW_PTR_SVAL as | |
2506 | non-null. | |
2507 | ||
2508 | This is similar to on_deallocator_call and on_allocator_call, | |
2509 | but the checks happen in on_realloc_call, and by splitting the states. */ | |
2510 | ||
2511 | void | |
2512 | malloc_state_machine:: | |
2513 | on_realloc_with_move (region_model *model, | |
2514 | sm_state_map *smap, | |
2515 | const svalue *old_ptr_sval, | |
2516 | const svalue *new_ptr_sval, | |
2517 | const extrinsic_state &ext_state) const | |
2518 | { | |
2519 | smap->set_state (model, old_ptr_sval, | |
2520 | m_free.m_deallocator.m_freed, | |
2521 | NULL, ext_state); | |
2522 | ||
2523 | smap->set_state (model, new_ptr_sval, | |
2524 | m_free.m_nonnull, | |
2525 | NULL, ext_state); | |
2526 | } | |
2527 | ||
2528 | /* Hook for get_or_create_region_for_heap_alloc for the case when we want | |
2529 | ptr_sval to mark a newly created region as assumed non null on malloc SM. */ | |
2530 | void | |
2531 | malloc_state_machine::transition_ptr_sval_non_null (region_model *model, | |
2532 | sm_state_map *smap, | |
2533 | const svalue *new_ptr_sval, | |
2534 | const extrinsic_state &ext_state) const | |
2535 | { | |
2536 | smap->set_state (model, new_ptr_sval, m_free.m_nonnull, NULL, ext_state); | |
2537 | } | |
2538 | ||
2539 | } // anonymous namespace | |
2540 | ||
2541 | /* Internal interface to this file. */ | |
2542 | ||
2543 | state_machine * | |
2544 | make_malloc_state_machine (logger *logger) | |
2545 | { | |
2546 | return new malloc_state_machine (logger); | |
2547 | } | |
2548 | ||
2549 | /* Specialcase hook for handling realloc, for use by | |
2550 | kf_realloc::impl_call_post::success_with_move::update_model. */ | |
2551 | ||
2552 | void | |
2553 | region_model::on_realloc_with_move (const call_details &cd, | |
2554 | const svalue *old_ptr_sval, | |
2555 | const svalue *new_ptr_sval) | |
2556 | { | |
2557 | region_model_context *ctxt = cd.get_ctxt (); | |
2558 | if (!ctxt) | |
2559 | return; | |
2560 | const extrinsic_state *ext_state = ctxt->get_ext_state (); | |
2561 | if (!ext_state) | |
2562 | return; | |
2563 | ||
2564 | sm_state_map *smap; | |
2565 | const state_machine *sm; | |
2566 | unsigned sm_idx; | |
2567 | if (!ctxt->get_malloc_map (&smap, &sm, &sm_idx)) | |
2568 | return; | |
2569 | ||
2570 | gcc_assert (smap); | |
2571 | gcc_assert (sm); | |
2572 | ||
2573 | const malloc_state_machine &malloc_sm | |
2574 | = (const malloc_state_machine &)*sm; | |
2575 | ||
2576 | malloc_sm.on_realloc_with_move (this, | |
2577 | smap, | |
2578 | old_ptr_sval, | |
2579 | new_ptr_sval, | |
2580 | *ext_state); | |
2581 | } | |
2582 | ||
2583 | /* Moves ptr_sval from start to assumed non-null, for use by | |
2584 | region_model::get_or_create_region_for_heap_alloc. */ | |
2585 | void | |
2586 | region_model::transition_ptr_sval_non_null (region_model_context *ctxt, | |
2587 | const svalue *ptr_sval) | |
2588 | { | |
2589 | if (!ctxt) | |
2590 | return; | |
2591 | const extrinsic_state *ext_state = ctxt->get_ext_state (); | |
2592 | if (!ext_state) | |
2593 | return; | |
2594 | ||
2595 | sm_state_map *smap; | |
2596 | const state_machine *sm; | |
2597 | unsigned sm_idx; | |
2598 | if (!ctxt->get_malloc_map (&smap, &sm, &sm_idx)) | |
2599 | return; | |
2600 | ||
2601 | gcc_assert (smap); | |
2602 | gcc_assert (sm); | |
2603 | ||
2604 | const malloc_state_machine &malloc_sm = (const malloc_state_machine &)*sm; | |
2605 | ||
2606 | malloc_sm.transition_ptr_sval_non_null (this, smap, ptr_sval, *ext_state); | |
2607 | } | |
2608 | ||
2609 | } // namespace ana | |
2610 | ||
2611 | #endif /* #if ENABLE_ANALYZER */ |