perf dwarf-aux: Fix libdw API contract violations

Check return values of `dwarf_decl_line` (where non-optional),
`dwarf_getfuncs`, and `dwarf_lineaddr` to prevent using uninitialized
stack variables or incorrectly reporting success on failure.

For the root DIE in `die_walk_lines()`, `dwarf_decl_line` and
`die_get_decl_file` are optional and their failures are handled
gracefully to avoid breaking line walking on valid functions.
Specifically, remove the strict `!decf` (declared file) check that
would prematurely abort line walking on generated or artificial
functions lacking this optional attribute.

Additionally:
 - Add NULL pointer protection for `strcmp()` in `die_walk_lines()`
   when `inf` or `decf` are NULL to prevent crashes on generated
   code.
 - Use `dwarf_attr_integrate` in `die_get_data_member_location` to
   correctly resolve inherited member locations (e.g. via abstract
   origin or specification).

Fixes: 57f95bf5f882 ("perf probe: Show correct statement line number by perf probe -l")
Fixes: 3f4460a28fb2 ("perf probe: Filter out redundant inline-instances")
Fixes: 75186a9b09e4 ("perf probe: Fix to show lines of sys_ functions correctly")
Fixes: e0d153c69040 ("perf-probe: Move dwarf library routines to dwarf-aux.{c, h}")
Fixes: 6243b9dc4c99 ("perf probe: Move dwarf specific functions to dwarf-aux.c")
Assisted-by: Gemini-CLI:Google Gemini 3
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zecheng Li <zli94@ncsu.edu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 109a166a6d19cedbbb03bbbaae7c2e6f3016a894..d7160f87ac7d7ab36037d2ef3ef1e95a5ff5746b 100644 (file)
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -125,7 +125,8 @@ int cu_find_lineinfo(Dwarf_Die *cu_die, Dwarf_Addr addr,
            && die_entrypc(&die_mem, &faddr) == 0 &&
            faddr == addr) {
                *fname = die_get_decl_file(&die_mem);
-               dwarf_decl_line(&die_mem, lineno);
+               if (dwarf_decl_line(&die_mem, lineno) != 0)
+                       return -ENOENT;
                goto out;
        }
 
@@ -459,7 +460,7 @@ int die_get_data_member_location(Dwarf_Die *mb_die, Dwarf_Word *offs)
        size_t nexpr;
        int ret;
 
-       if (dwarf_attr(mb_die, DW_AT_data_member_location, &attr) == NULL)
+       if (dwarf_attr_integrate(mb_die, DW_AT_data_member_location, &attr) == NULL)
                return -ENOENT;
 
        if (dwarf_formudata(&attr, offs) != 0) {
@@ -795,8 +796,7 @@ static int __die_walk_instances_cb(Dwarf_Die *inst, void *data)
 
        /* Ignore redundant instances */
        if (dwarf_tag(inst) == DW_TAG_inlined_subroutine) {
-               dwarf_decl_line(origin, &tmp);
-               if (die_get_call_lineno(inst) == tmp) {
+               if (dwarf_decl_line(origin, &tmp) == 0 && die_get_call_lineno(inst) == tmp) {
                        tmp = die_get_decl_fileno(origin);
                        if (die_get_call_fileno(inst) == tmp)
                                return DIE_FIND_CB_CONTINUE;
@@ -950,11 +950,6 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
                cu_die = dwarf_diecu(rt_die, &die_mem, NULL, NULL);
                dwarf_decl_line(rt_die, &decl);
                decf = die_get_decl_file(rt_die);
-               if (!decf) {
-                       pr_debug2("Failed to get the declared file name of %s\n",
-                                 dwarf_diename(rt_die));
-                       return -EINVAL;
-               }
        } else
                cu_die = rt_die;
        if (!cu_die) {
@@ -998,11 +993,12 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
                        if (die_find_inlinefunc(rt_die, addr, &die_mem)) {
                                /* Call-site check */
                                inf = die_get_call_file(&die_mem);
-                               if ((inf && !strcmp(inf, decf)) &&
+                               if ((inf == decf || (inf && decf && !strcmp(inf, decf))) &&
                                    die_get_call_lineno(&die_mem) == lineno)
                                        goto found;
 
-                               dwarf_decl_line(&die_mem, &inl);
+                               if (dwarf_decl_line(&die_mem, &inl) != 0)
+                                       inl = 0;
                                if (inl != decl ||
                                    decf != die_get_decl_file(&die_mem))
                                        continue;
@@ -1034,8 +1030,10 @@ found:
                        .data = data,
                        .retval = 0,
                };
-               dwarf_getfuncs(cu_die, __die_walk_culines_cb, &param, 0);
-               ret = param.retval;
+               if (dwarf_getfuncs(cu_die, __die_walk_culines_cb, &param, 0) < 0)
+                       ret = -EINVAL;
+               else
+                       ret = param.retval;
        }
 
        return ret;
@@ -1939,10 +1937,12 @@ static bool die_get_postprologue_addr(unsigned long entrypc_idx,
                        break;
        }
 
-       dwarf_lineaddr(line, postprologue_addr);
-       if (*postprologue_addr >= highpc)
-               dwarf_lineaddr(dwarf_onesrcline(lines, i - 1),
-                              postprologue_addr);
+       if (dwarf_lineaddr(line, postprologue_addr) != 0)
+               return false;
+       if (*postprologue_addr >= highpc) {
+               if (dwarf_lineaddr(dwarf_onesrcline(lines, i - 1), postprologue_addr) != 0)
+                       return false;
+       }
 
        return true;
 }

diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
index a79968a2e573b3e15eb64425d00d4c452f39a74a..161f0bf980b6ee6acda48f9007e1c9b241afa679 100644 (file)
--- a/tools/perf/util/dwarf-aux.h
+++ b/tools/perf/util/dwarf-aux.h
@@ -10,6 +10,11 @@
 #include <elfutils/libdwfl.h>
 #include <elfutils/version.h>
 
+static inline const char *die_name(Dwarf_Die *die)
+{
+       return dwarf_diename(die) ?: "<unknown>";
+}
+
 struct strbuf;
 
 /* Find the realpath of the target file */