libsanitizer/asan/asan_report.cpp

   1 //===-- asan_report.cpp ---------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is a part of AddressSanitizer, an address sanity checker.
  10 //
  11 // This file contains error reporting code.
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "asan_errors.h"
  15 #include "asan_flags.h"
  16 #include "asan_descriptions.h"
  17 #include "asan_internal.h"
  18 #include "asan_mapping.h"
  19 #include "asan_report.h"
  20 #include "asan_scariness_score.h"
  21 #include "asan_stack.h"
  22 #include "asan_thread.h"
  23 #include "sanitizer_common/sanitizer_common.h"
  24 #include "sanitizer_common/sanitizer_flags.h"
  25 #include "sanitizer_common/sanitizer_report_decorator.h"
  26 #include "sanitizer_common/sanitizer_stackdepot.h"
  27 #include "sanitizer_common/sanitizer_symbolizer.h"
  28
  29 namespace __asan {
  30
  31 // -------------------- User-specified callbacks ----------------- {{{1
  32 static void (*error_report_callback)(const char*);
  33 static char *error_message_buffer = nullptr;
  34 static uptr error_message_buffer_pos = 0;
  35 static BlockingMutex error_message_buf_mutex(LINKER_INITIALIZED);
  36 static const unsigned kAsanBuggyPcPoolSize = 25;
  37 static __sanitizer::atomic_uintptr_t AsanBuggyPcPool[kAsanBuggyPcPoolSize];
  38
  39 void AppendToErrorMessageBuffer(const char *buffer) {
  40   BlockingMutexLock l(&error_message_buf_mutex);
  41   if (!error_message_buffer) {
  42     error_message_buffer =
  43       (char*)MmapOrDieQuietly(kErrorMessageBufferSize, __func__);
  44     error_message_buffer_pos = 0;
  45   }
  46   uptr length = internal_strlen(buffer);
  47   RAW_CHECK(kErrorMessageBufferSize >= error_message_buffer_pos);
  48   uptr remaining = kErrorMessageBufferSize - error_message_buffer_pos;
  49   internal_strncpy(error_message_buffer + error_message_buffer_pos,
  50                    buffer, remaining);
  51   error_message_buffer[kErrorMessageBufferSize - 1] = '\0';
  52   // FIXME: reallocate the buffer instead of truncating the message.
  53   error_message_buffer_pos += Min(remaining, length);
  54 }
  55
  56 // ---------------------- Helper functions ----------------------- {{{1
  57
  58 void PrintMemoryByte(InternalScopedString *str, const char *before, u8 byte,
  59                      bool in_shadow, const char *after) {
  60   Decorator d;
  61   str->append("%s%s%x%x%s%s", before,
  62               in_shadow ? d.ShadowByte(byte) : d.MemoryByte(), byte >> 4,
  63               byte & 15, d.Default(), after);
  64 }
  65
  66 static void PrintZoneForPointer(uptr ptr, uptr zone_ptr,
  67                                 const char *zone_name) {
  68   if (zone_ptr) {
  69     if (zone_name) {
  70       Printf("malloc_zone_from_ptr(%p) = %p, which is %s\n",
  71                  ptr, zone_ptr, zone_name);
  72     } else {
  73       Printf("malloc_zone_from_ptr(%p) = %p, which doesn't have a name\n",
  74                  ptr, zone_ptr);
  75     }
  76   } else {
  77     Printf("malloc_zone_from_ptr(%p) = 0\n", ptr);
  78   }
  79 }
  80
  81 // ---------------------- Address Descriptions ------------------- {{{1
  82
  83 bool ParseFrameDescription(const char *frame_descr,
  84                            InternalMmapVector<StackVarDescr> *vars) {
  85   CHECK(frame_descr);
  86   const char *p;
  87   // This string is created by the compiler and has the following form:
  88   // "n alloc_1 alloc_2 ... alloc_n"
  89   // where alloc_i looks like "offset size len ObjectName"
  90   // or                       "offset size len ObjectName:line".
  91   uptr n_objects = (uptr)internal_simple_strtoll(frame_descr, &p, 10);
  92   if (n_objects == 0)
  93     return false;
  94
  95   for (uptr i = 0; i < n_objects; i++) {
  96     uptr beg  = (uptr)internal_simple_strtoll(p, &p, 10);
  97     uptr size = (uptr)internal_simple_strtoll(p, &p, 10);
  98     uptr len  = (uptr)internal_simple_strtoll(p, &p, 10);
  99     if (beg == 0 || size == 0 || *p != ' ') {
 100       return false;
 101     }
 102     p++;
 103     char *colon_pos = internal_strchr(p, ':');
 104     uptr line = 0;
 105     uptr name_len = len;
 106     if (colon_pos != nullptr && colon_pos < p + len) {
 107       name_len = colon_pos - p;
 108       line = (uptr)internal_simple_strtoll(colon_pos + 1, nullptr, 10);
 109     }
 110     StackVarDescr var = {beg, size, p, name_len, line};
 111     vars->push_back(var);
 112     p += len;
 113   }
 114
 115   return true;
 116 }
 117
 118 // -------------------- Different kinds of reports ----------------- {{{1
 119
 120 // Use ScopedInErrorReport to run common actions just before and
 121 // immediately after printing error report.
 122 class ScopedInErrorReport {
 123  public:
 124   explicit ScopedInErrorReport(bool fatal = false)
 125       : halt_on_error_(fatal || flags()->halt_on_error) {
 126     // Make sure the registry and sanitizer report mutexes are locked while
 127     // we're printing an error report.
 128     // We can lock them only here to avoid self-deadlock in case of
 129     // recursive reports.
 130     asanThreadRegistry().Lock();
 131     Printf(
 132         "=================================================================\n");
 133   }
 134
 135   ~ScopedInErrorReport() {
 136     if (halt_on_error_ && !__sanitizer_acquire_crash_state()) {
 137       asanThreadRegistry().Unlock();
 138       return;
 139     }
 140     ASAN_ON_ERROR();
 141     if (current_error_.IsValid()) current_error_.Print();
 142
 143     // Make sure the current thread is announced.
 144     DescribeThread(GetCurrentThread());
 145     // We may want to grab this lock again when printing stats.
 146     asanThreadRegistry().Unlock();
 147     // Print memory stats.
 148     if (flags()->print_stats)
 149       __asan_print_accumulated_stats();
 150
 151     if (common_flags()->print_cmdline)
 152       PrintCmdline();
 153
 154     if (common_flags()->print_module_map == 2) PrintModuleMap();
 155
 156     // Copy the message buffer so that we could start logging without holding a
 157     // lock that gets aquired during printing.
 158     InternalMmapVector<char> buffer_copy(kErrorMessageBufferSize);
 159     {
 160       BlockingMutexLock l(&error_message_buf_mutex);
 161       internal_memcpy(buffer_copy.data(),
 162                       error_message_buffer, kErrorMessageBufferSize);
 163       // Clear error_message_buffer so that if we find other errors
 164       // we don't re-log this error.
 165       error_message_buffer_pos = 0;
 166     }
 167
 168     LogFullErrorReport(buffer_copy.data());
 169
 170     if (error_report_callback) {
 171       error_report_callback(buffer_copy.data());
 172     }
 173
 174     if (halt_on_error_ && common_flags()->abort_on_error) {
 175       // On Android the message is truncated to 512 characters.
 176       // FIXME: implement "compact" error format, possibly without, or with
 177       // highly compressed stack traces?
 178       // FIXME: or just use the summary line as abort message?
 179       SetAbortMessage(buffer_copy.data());
 180     }
 181
 182     // In halt_on_error = false mode, reset the current error object (before
 183     // unlocking).
 184     if (!halt_on_error_)
 185       internal_memset(&current_error_, 0, sizeof(current_error_));
 186
 187     if (halt_on_error_) {
 188       Report("ABORTING\n");
 189       Die();
 190     }
 191   }
 192
 193   void ReportError(const ErrorDescription &description) {
 194     // Can only report one error per ScopedInErrorReport.
 195     CHECK_EQ(current_error_.kind, kErrorKindInvalid);
 196     internal_memcpy(&current_error_, &description, sizeof(current_error_));
 197   }
 198
 199   static ErrorDescription &CurrentError() {
 200     return current_error_;
 201   }
 202
 203  private:
 204   ScopedErrorReportLock error_report_lock_;
 205   // Error currently being reported. This enables the destructor to interact
 206   // with the debugger and point it to an error description.
 207   static ErrorDescription current_error_;
 208   bool halt_on_error_;
 209 };
 210
 211 ErrorDescription ScopedInErrorReport::current_error_(LINKER_INITIALIZED);
 212
 213 void ReportDeadlySignal(const SignalContext &sig) {
 214   ScopedInErrorReport in_report(/*fatal*/ true);
 215   ErrorDeadlySignal error(GetCurrentTidOrInvalid(), sig);
 216   in_report.ReportError(error);
 217 }
 218
 219 void ReportDoubleFree(uptr addr, BufferedStackTrace *free_stack) {
 220   ScopedInErrorReport in_report;
 221   ErrorDoubleFree error(GetCurrentTidOrInvalid(), free_stack, addr);
 222   in_report.ReportError(error);
 223 }
 224
 225 void ReportNewDeleteTypeMismatch(uptr addr, uptr delete_size,
 226                                  uptr delete_alignment,
 227                                  BufferedStackTrace *free_stack) {
 228   ScopedInErrorReport in_report;
 229   ErrorNewDeleteTypeMismatch error(GetCurrentTidOrInvalid(), free_stack, addr,
 230                                    delete_size, delete_alignment);
 231   in_report.ReportError(error);
 232 }
 233
 234 void ReportFreeNotMalloced(uptr addr, BufferedStackTrace *free_stack) {
 235   ScopedInErrorReport in_report;
 236   ErrorFreeNotMalloced error(GetCurrentTidOrInvalid(), free_stack, addr);
 237   in_report.ReportError(error);
 238 }
 239
 240 void ReportAllocTypeMismatch(uptr addr, BufferedStackTrace *free_stack,
 241                              AllocType alloc_type,
 242                              AllocType dealloc_type) {
 243   ScopedInErrorReport in_report;
 244   ErrorAllocTypeMismatch error(GetCurrentTidOrInvalid(), free_stack, addr,
 245                                alloc_type, dealloc_type);
 246   in_report.ReportError(error);
 247 }
 248
 249 void ReportMallocUsableSizeNotOwned(uptr addr, BufferedStackTrace *stack) {
 250   ScopedInErrorReport in_report;
 251   ErrorMallocUsableSizeNotOwned error(GetCurrentTidOrInvalid(), stack, addr);
 252   in_report.ReportError(error);
 253 }
 254
 255 void ReportSanitizerGetAllocatedSizeNotOwned(uptr addr,
 256                                              BufferedStackTrace *stack) {
 257   ScopedInErrorReport in_report;
 258   ErrorSanitizerGetAllocatedSizeNotOwned error(GetCurrentTidOrInvalid(), stack,
 259                                                addr);
 260   in_report.ReportError(error);
 261 }
 262
 263 void ReportCallocOverflow(uptr count, uptr size, BufferedStackTrace *stack) {
 264   ScopedInErrorReport in_report(/*fatal*/ true);
 265   ErrorCallocOverflow error(GetCurrentTidOrInvalid(), stack, count, size);
 266   in_report.ReportError(error);
 267 }
 268
 269 void ReportReallocArrayOverflow(uptr count, uptr size,
 270                                 BufferedStackTrace *stack) {
 271   ScopedInErrorReport in_report(/*fatal*/ true);
 272   ErrorReallocArrayOverflow error(GetCurrentTidOrInvalid(), stack, count, size);
 273   in_report.ReportError(error);
 274 }
 275
 276 void ReportPvallocOverflow(uptr size, BufferedStackTrace *stack) {
 277   ScopedInErrorReport in_report(/*fatal*/ true);
 278   ErrorPvallocOverflow error(GetCurrentTidOrInvalid(), stack, size);
 279   in_report.ReportError(error);
 280 }
 281
 282 void ReportInvalidAllocationAlignment(uptr alignment,
 283                                       BufferedStackTrace *stack) {
 284   ScopedInErrorReport in_report(/*fatal*/ true);
 285   ErrorInvalidAllocationAlignment error(GetCurrentTidOrInvalid(), stack,
 286                                         alignment);
 287   in_report.ReportError(error);
 288 }
 289
 290 void ReportInvalidAlignedAllocAlignment(uptr size, uptr alignment,
 291                                         BufferedStackTrace *stack) {
 292   ScopedInErrorReport in_report(/*fatal*/ true);
 293   ErrorInvalidAlignedAllocAlignment error(GetCurrentTidOrInvalid(), stack,
 294                                           size, alignment);
 295   in_report.ReportError(error);
 296 }
 297
 298 void ReportInvalidPosixMemalignAlignment(uptr alignment,
 299                                          BufferedStackTrace *stack) {
 300   ScopedInErrorReport in_report(/*fatal*/ true);
 301   ErrorInvalidPosixMemalignAlignment error(GetCurrentTidOrInvalid(), stack,
 302                                            alignment);
 303   in_report.ReportError(error);
 304 }
 305
 306 void ReportAllocationSizeTooBig(uptr user_size, uptr total_size, uptr max_size,
 307                                 BufferedStackTrace *stack) {
 308   ScopedInErrorReport in_report(/*fatal*/ true);
 309   ErrorAllocationSizeTooBig error(GetCurrentTidOrInvalid(), stack, user_size,
 310                                   total_size, max_size);
 311   in_report.ReportError(error);
 312 }
 313
 314 void ReportRssLimitExceeded(BufferedStackTrace *stack) {
 315   ScopedInErrorReport in_report(/*fatal*/ true);
 316   ErrorRssLimitExceeded error(GetCurrentTidOrInvalid(), stack);
 317   in_report.ReportError(error);
 318 }
 319
 320 void ReportOutOfMemory(uptr requested_size, BufferedStackTrace *stack) {
 321   ScopedInErrorReport in_report(/*fatal*/ true);
 322   ErrorOutOfMemory error(GetCurrentTidOrInvalid(), stack, requested_size);
 323   in_report.ReportError(error);
 324 }
 325
 326 void ReportStringFunctionMemoryRangesOverlap(const char *function,
 327                                              const char *offset1, uptr length1,
 328                                              const char *offset2, uptr length2,
 329                                              BufferedStackTrace *stack) {
 330   ScopedInErrorReport in_report;
 331   ErrorStringFunctionMemoryRangesOverlap error(
 332       GetCurrentTidOrInvalid(), stack, (uptr)offset1, length1, (uptr)offset2,
 333       length2, function);
 334   in_report.ReportError(error);
 335 }
 336
 337 void ReportStringFunctionSizeOverflow(uptr offset, uptr size,
 338                                       BufferedStackTrace *stack) {
 339   ScopedInErrorReport in_report;
 340   ErrorStringFunctionSizeOverflow error(GetCurrentTidOrInvalid(), stack, offset,
 341                                         size);
 342   in_report.ReportError(error);
 343 }
 344
 345 void ReportBadParamsToAnnotateContiguousContainer(uptr beg, uptr end,
 346                                                   uptr old_mid, uptr new_mid,
 347                                                   BufferedStackTrace *stack) {
 348   ScopedInErrorReport in_report;
 349   ErrorBadParamsToAnnotateContiguousContainer error(
 350       GetCurrentTidOrInvalid(), stack, beg, end, old_mid, new_mid);
 351   in_report.ReportError(error);
 352 }
 353
 354 void ReportODRViolation(const __asan_global *g1, u32 stack_id1,
 355                         const __asan_global *g2, u32 stack_id2) {
 356   ScopedInErrorReport in_report;
 357   ErrorODRViolation error(GetCurrentTidOrInvalid(), g1, stack_id1, g2,
 358                           stack_id2);
 359   in_report.ReportError(error);
 360 }
 361
 362 // ----------------------- CheckForInvalidPointerPair ----------- {{{1
 363 static NOINLINE void ReportInvalidPointerPair(uptr pc, uptr bp, uptr sp,
 364                                               uptr a1, uptr a2) {
 365   ScopedInErrorReport in_report;
 366   ErrorInvalidPointerPair error(GetCurrentTidOrInvalid(), pc, bp, sp, a1, a2);
 367   in_report.ReportError(error);
 368 }
 369
 370 static bool IsInvalidPointerPair(uptr a1, uptr a2) {
 371   if (a1 == a2)
 372     return false;
 373
 374   // 256B in shadow memory can be iterated quite fast
 375   static const uptr kMaxOffset = 2048;
 376
 377   uptr left = a1 < a2 ? a1 : a2;
 378   uptr right = a1 < a2 ? a2 : a1;
 379   uptr offset = right - left;
 380   if (offset <= kMaxOffset)
 381     return __asan_region_is_poisoned(left, offset);
 382
 383   AsanThread *t = GetCurrentThread();
 384
 385   // check whether left is a stack memory pointer
 386   if (uptr shadow_offset1 = t->GetStackVariableShadowStart(left)) {
 387     uptr shadow_offset2 = t->GetStackVariableShadowStart(right);
 388     return shadow_offset2 == 0 || shadow_offset1 != shadow_offset2;
 389   }
 390
 391   // check whether left is a heap memory address
 392   HeapAddressDescription hdesc1, hdesc2;
 393   if (GetHeapAddressInformation(left, 0, &hdesc1) &&
 394       hdesc1.chunk_access.access_type == kAccessTypeInside)
 395     return !GetHeapAddressInformation(right, 0, &hdesc2) ||
 396         hdesc2.chunk_access.access_type != kAccessTypeInside ||
 397         hdesc1.chunk_access.chunk_begin != hdesc2.chunk_access.chunk_begin;
 398
 399   // check whether left is an address of a global variable
 400   GlobalAddressDescription gdesc1, gdesc2;
 401   if (GetGlobalAddressInformation(left, 0, &gdesc1))
 402     return !GetGlobalAddressInformation(right - 1, 0, &gdesc2) ||
 403         !gdesc1.PointsInsideTheSameVariable(gdesc2);
 404
 405   if (t->GetStackVariableShadowStart(right) ||
 406       GetHeapAddressInformation(right, 0, &hdesc2) ||
 407       GetGlobalAddressInformation(right - 1, 0, &gdesc2))
 408     return true;
 409
 410   // At this point we know nothing about both a1 and a2 addresses.
 411   return false;
 412 }
 413
 414 static INLINE void CheckForInvalidPointerPair(void *p1, void *p2) {
 415   switch (flags()->detect_invalid_pointer_pairs) {
 416     case 0:
 417       return;
 418     case 1:
 419       if (p1 == nullptr || p2 == nullptr)
 420         return;
 421       break;
 422   }
 423
 424   uptr a1 = reinterpret_cast<uptr>(p1);
 425   uptr a2 = reinterpret_cast<uptr>(p2);
 426
 427   if (IsInvalidPointerPair(a1, a2)) {
 428     GET_CALLER_PC_BP_SP;
 429     ReportInvalidPointerPair(pc, bp, sp, a1, a2);
 430   }
 431 }
 432 // ----------------------- Mac-specific reports ----------------- {{{1
 433
 434 void ReportMacMzReallocUnknown(uptr addr, uptr zone_ptr, const char *zone_name,
 435                                BufferedStackTrace *stack) {
 436   ScopedInErrorReport in_report;
 437   Printf("mz_realloc(%p) -- attempting to realloc unallocated memory.\n"
 438              "This is an unrecoverable problem, exiting now.\n",
 439              addr);
 440   PrintZoneForPointer(addr, zone_ptr, zone_name);
 441   stack->Print();
 442   DescribeAddressIfHeap(addr);
 443 }
 444
 445 // -------------- SuppressErrorReport -------------- {{{1
 446 // Avoid error reports duplicating for ASan recover mode.
 447 static bool SuppressErrorReport(uptr pc) {
 448   if (!common_flags()->suppress_equal_pcs) return false;
 449   for (unsigned i = 0; i < kAsanBuggyPcPoolSize; i++) {
 450     uptr cmp = atomic_load_relaxed(&AsanBuggyPcPool[i]);
 451     if (cmp == 0 && atomic_compare_exchange_strong(&AsanBuggyPcPool[i], &cmp,
 452                                                    pc, memory_order_relaxed))
 453       return false;
 454     if (cmp == pc) return true;
 455   }
 456   Die();
 457 }
 458
 459 void ReportGenericError(uptr pc, uptr bp, uptr sp, uptr addr, bool is_write,
 460                         uptr access_size, u32 exp, bool fatal) {
 461   if (!fatal && SuppressErrorReport(pc)) return;
 462   ENABLE_FRAME_POINTER;
 463
 464   // Optimization experiments.
 465   // The experiments can be used to evaluate potential optimizations that remove
 466   // instrumentation (assess false negatives). Instead of completely removing
 467   // some instrumentation, compiler can emit special calls into runtime
 468   // (e.g. __asan_report_exp_load1 instead of __asan_report_load1) and pass
 469   // mask of experiments (exp).
 470   // The reaction to a non-zero value of exp is to be defined.
 471   (void)exp;
 472
 473   ScopedInErrorReport in_report(fatal);
 474   ErrorGeneric error(GetCurrentTidOrInvalid(), pc, bp, sp, addr, is_write,
 475                      access_size);
 476   in_report.ReportError(error);
 477 }
 478
 479 }  // namespace __asan
 480
 481 // --------------------------- Interface --------------------- {{{1
 482 using namespace __asan;
 483
 484 void __asan_report_error(uptr pc, uptr bp, uptr sp, uptr addr, int is_write,
 485                          uptr access_size, u32 exp) {
 486   ENABLE_FRAME_POINTER;
 487   bool fatal = flags()->halt_on_error;
 488   ReportGenericError(pc, bp, sp, addr, is_write, access_size, exp, fatal);
 489 }
 490
 491 void NOINLINE __asan_set_error_report_callback(void (*callback)(const char*)) {
 492   BlockingMutexLock l(&error_message_buf_mutex);
 493   error_report_callback = callback;
 494 }
 495
 496 void __asan_describe_address(uptr addr) {
 497   // Thread registry must be locked while we're describing an address.
 498   asanThreadRegistry().Lock();
 499   PrintAddressDescription(addr, 1, "");
 500   asanThreadRegistry().Unlock();
 501 }
 502
 503 int __asan_report_present() {
 504   return ScopedInErrorReport::CurrentError().kind != kErrorKindInvalid;
 505 }
 506
 507 uptr __asan_get_report_pc() {
 508   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 509     return ScopedInErrorReport::CurrentError().Generic.pc;
 510   return 0;
 511 }
 512
 513 uptr __asan_get_report_bp() {
 514   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 515     return ScopedInErrorReport::CurrentError().Generic.bp;
 516   return 0;
 517 }
 518
 519 uptr __asan_get_report_sp() {
 520   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 521     return ScopedInErrorReport::CurrentError().Generic.sp;
 522   return 0;
 523 }
 524
 525 uptr __asan_get_report_address() {
 526   ErrorDescription &err = ScopedInErrorReport::CurrentError();
 527   if (err.kind == kErrorKindGeneric)
 528     return err.Generic.addr_description.Address();
 529   else if (err.kind == kErrorKindDoubleFree)
 530     return err.DoubleFree.addr_description.addr;
 531   return 0;
 532 }
 533
 534 int __asan_get_report_access_type() {
 535   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 536     return ScopedInErrorReport::CurrentError().Generic.is_write;
 537   return 0;
 538 }
 539
 540 uptr __asan_get_report_access_size() {
 541   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 542     return ScopedInErrorReport::CurrentError().Generic.access_size;
 543   return 0;
 544 }
 545
 546 const char *__asan_get_report_description() {
 547   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 548     return ScopedInErrorReport::CurrentError().Generic.bug_descr;
 549   return ScopedInErrorReport::CurrentError().Base.scariness.GetDescription();
 550 }
 551
 552 extern "C" {
 553 SANITIZER_INTERFACE_ATTRIBUTE
 554 void __sanitizer_ptr_sub(void *a, void *b) {
 555   CheckForInvalidPointerPair(a, b);
 556 }
 557 SANITIZER_INTERFACE_ATTRIBUTE
 558 void __sanitizer_ptr_cmp(void *a, void *b) {
 559   CheckForInvalidPointerPair(a, b);
 560 }
 561 } // extern "C"
 562
 563 // Provide default implementation of __asan_on_error that does nothing
 564 // and may be overriden by user.
 565 SANITIZER_INTERFACE_WEAK_DEF(void, __asan_on_error, void) {}