compiler-rt/lib/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)
 155       DumpProcessMap();
 156
 157     // Copy the message buffer so that we could start logging without holding a
 158     // lock that gets aquired during printing.
 159     InternalMmapVector<char> buffer_copy(kErrorMessageBufferSize);
 160     {
 161       BlockingMutexLock l(&error_message_buf_mutex);
 162       internal_memcpy(buffer_copy.data(),
 163                       error_message_buffer, kErrorMessageBufferSize);
 164       // Clear error_message_buffer so that if we find other errors
 165       // we don't re-log this error.
 166       error_message_buffer_pos = 0;
 167     }
 168
 169     LogFullErrorReport(buffer_copy.data());
 170
 171     if (error_report_callback) {
 172       error_report_callback(buffer_copy.data());
 173     }
 174
 175     if (halt_on_error_ && common_flags()->abort_on_error) {
 176       // On Android the message is truncated to 512 characters.
 177       // FIXME: implement "compact" error format, possibly without, or with
 178       // highly compressed stack traces?
 179       // FIXME: or just use the summary line as abort message?
 180       SetAbortMessage(buffer_copy.data());
 181     }
 182
 183     // In halt_on_error = false mode, reset the current error object (before
 184     // unlocking).
 185     if (!halt_on_error_)
 186       internal_memset(&current_error_, 0, sizeof(current_error_));
 187
 188     if (halt_on_error_) {
 189       Report("ABORTING\n");
 190       Die();
 191     }
 192   }
 193
 194   void ReportError(const ErrorDescription &description) {
 195     // Can only report one error per ScopedInErrorReport.
 196     CHECK_EQ(current_error_.kind, kErrorKindInvalid);
 197     internal_memcpy(&current_error_, &description, sizeof(current_error_));
 198   }
 199
 200   static ErrorDescription &CurrentError() {
 201     return current_error_;
 202   }
 203
 204  private:
 205   ScopedErrorReportLock error_report_lock_;
 206   // Error currently being reported. This enables the destructor to interact
 207   // with the debugger and point it to an error description.
 208   static ErrorDescription current_error_;
 209   bool halt_on_error_;
 210 };
 211
 212 ErrorDescription ScopedInErrorReport::current_error_(LINKER_INITIALIZED);
 213
 214 void ReportDeadlySignal(const SignalContext &sig) {
 215   ScopedInErrorReport in_report(/*fatal*/ true);
 216   ErrorDeadlySignal error(GetCurrentTidOrInvalid(), sig);
 217   in_report.ReportError(error);
 218 }
 219
 220 void ReportDoubleFree(uptr addr, BufferedStackTrace *free_stack) {
 221   ScopedInErrorReport in_report;
 222   ErrorDoubleFree error(GetCurrentTidOrInvalid(), free_stack, addr);
 223   in_report.ReportError(error);
 224 }
 225
 226 void ReportNewDeleteTypeMismatch(uptr addr, uptr delete_size,
 227                                  uptr delete_alignment,
 228                                  BufferedStackTrace *free_stack) {
 229   ScopedInErrorReport in_report;
 230   ErrorNewDeleteTypeMismatch error(GetCurrentTidOrInvalid(), free_stack, addr,
 231                                    delete_size, delete_alignment);
 232   in_report.ReportError(error);
 233 }
 234
 235 void ReportFreeNotMalloced(uptr addr, BufferedStackTrace *free_stack) {
 236   ScopedInErrorReport in_report;
 237   ErrorFreeNotMalloced error(GetCurrentTidOrInvalid(), free_stack, addr);
 238   in_report.ReportError(error);
 239 }
 240
 241 void ReportAllocTypeMismatch(uptr addr, BufferedStackTrace *free_stack,
 242                              AllocType alloc_type,
 243                              AllocType dealloc_type) {
 244   ScopedInErrorReport in_report;
 245   ErrorAllocTypeMismatch error(GetCurrentTidOrInvalid(), free_stack, addr,
 246                                alloc_type, dealloc_type);
 247   in_report.ReportError(error);
 248 }
 249
 250 void ReportMallocUsableSizeNotOwned(uptr addr, BufferedStackTrace *stack) {
 251   ScopedInErrorReport in_report;
 252   ErrorMallocUsableSizeNotOwned error(GetCurrentTidOrInvalid(), stack, addr);
 253   in_report.ReportError(error);
 254 }
 255
 256 void ReportSanitizerGetAllocatedSizeNotOwned(uptr addr,
 257                                              BufferedStackTrace *stack) {
 258   ScopedInErrorReport in_report;
 259   ErrorSanitizerGetAllocatedSizeNotOwned error(GetCurrentTidOrInvalid(), stack,
 260                                                addr);
 261   in_report.ReportError(error);
 262 }
 263
 264 void ReportCallocOverflow(uptr count, uptr size, BufferedStackTrace *stack) {
 265   ScopedInErrorReport in_report(/*fatal*/ true);
 266   ErrorCallocOverflow error(GetCurrentTidOrInvalid(), stack, count, size);
 267   in_report.ReportError(error);
 268 }
 269
 270 void ReportReallocArrayOverflow(uptr count, uptr size,
 271                                 BufferedStackTrace *stack) {
 272   ScopedInErrorReport in_report(/*fatal*/ true);
 273   ErrorReallocArrayOverflow error(GetCurrentTidOrInvalid(), stack, count, size);
 274   in_report.ReportError(error);
 275 }
 276
 277 void ReportPvallocOverflow(uptr size, BufferedStackTrace *stack) {
 278   ScopedInErrorReport in_report(/*fatal*/ true);
 279   ErrorPvallocOverflow error(GetCurrentTidOrInvalid(), stack, size);
 280   in_report.ReportError(error);
 281 }
 282
 283 void ReportInvalidAllocationAlignment(uptr alignment,
 284                                       BufferedStackTrace *stack) {
 285   ScopedInErrorReport in_report(/*fatal*/ true);
 286   ErrorInvalidAllocationAlignment error(GetCurrentTidOrInvalid(), stack,
 287                                         alignment);
 288   in_report.ReportError(error);
 289 }
 290
 291 void ReportInvalidAlignedAllocAlignment(uptr size, uptr alignment,
 292                                         BufferedStackTrace *stack) {
 293   ScopedInErrorReport in_report(/*fatal*/ true);
 294   ErrorInvalidAlignedAllocAlignment error(GetCurrentTidOrInvalid(), stack,
 295                                           size, alignment);
 296   in_report.ReportError(error);
 297 }
 298
 299 void ReportInvalidPosixMemalignAlignment(uptr alignment,
 300                                          BufferedStackTrace *stack) {
 301   ScopedInErrorReport in_report(/*fatal*/ true);
 302   ErrorInvalidPosixMemalignAlignment error(GetCurrentTidOrInvalid(), stack,
 303                                            alignment);
 304   in_report.ReportError(error);
 305 }
 306
 307 void ReportAllocationSizeTooBig(uptr user_size, uptr total_size, uptr max_size,
 308                                 BufferedStackTrace *stack) {
 309   ScopedInErrorReport in_report(/*fatal*/ true);
 310   ErrorAllocationSizeTooBig error(GetCurrentTidOrInvalid(), stack, user_size,
 311                                   total_size, max_size);
 312   in_report.ReportError(error);
 313 }
 314
 315 void ReportRssLimitExceeded(BufferedStackTrace *stack) {
 316   ScopedInErrorReport in_report(/*fatal*/ true);
 317   ErrorRssLimitExceeded error(GetCurrentTidOrInvalid(), stack);
 318   in_report.ReportError(error);
 319 }
 320
 321 void ReportOutOfMemory(uptr requested_size, BufferedStackTrace *stack) {
 322   ScopedInErrorReport in_report(/*fatal*/ true);
 323   ErrorOutOfMemory error(GetCurrentTidOrInvalid(), stack, requested_size);
 324   in_report.ReportError(error);
 325 }
 326
 327 void ReportStringFunctionMemoryRangesOverlap(const char *function,
 328                                              const char *offset1, uptr length1,
 329                                              const char *offset2, uptr length2,
 330                                              BufferedStackTrace *stack) {
 331   ScopedInErrorReport in_report;
 332   ErrorStringFunctionMemoryRangesOverlap error(
 333       GetCurrentTidOrInvalid(), stack, (uptr)offset1, length1, (uptr)offset2,
 334       length2, function);
 335   in_report.ReportError(error);
 336 }
 337
 338 void ReportStringFunctionSizeOverflow(uptr offset, uptr size,
 339                                       BufferedStackTrace *stack) {
 340   ScopedInErrorReport in_report;
 341   ErrorStringFunctionSizeOverflow error(GetCurrentTidOrInvalid(), stack, offset,
 342                                         size);
 343   in_report.ReportError(error);
 344 }
 345
 346 void ReportBadParamsToAnnotateContiguousContainer(uptr beg, uptr end,
 347                                                   uptr old_mid, uptr new_mid,
 348                                                   BufferedStackTrace *stack) {
 349   ScopedInErrorReport in_report;
 350   ErrorBadParamsToAnnotateContiguousContainer error(
 351       GetCurrentTidOrInvalid(), stack, beg, end, old_mid, new_mid);
 352   in_report.ReportError(error);
 353 }
 354
 355 void ReportODRViolation(const __asan_global *g1, u32 stack_id1,
 356                         const __asan_global *g2, u32 stack_id2) {
 357   ScopedInErrorReport in_report;
 358   ErrorODRViolation error(GetCurrentTidOrInvalid(), g1, stack_id1, g2,
 359                           stack_id2);
 360   in_report.ReportError(error);
 361 }
 362
 363 // ----------------------- CheckForInvalidPointerPair ----------- {{{1
 364 static NOINLINE void ReportInvalidPointerPair(uptr pc, uptr bp, uptr sp,
 365                                               uptr a1, uptr a2) {
 366   ScopedInErrorReport in_report;
 367   ErrorInvalidPointerPair error(GetCurrentTidOrInvalid(), pc, bp, sp, a1, a2);
 368   in_report.ReportError(error);
 369 }
 370
 371 static bool IsInvalidPointerPair(uptr a1, uptr a2) {
 372   if (a1 == a2)
 373     return false;
 374
 375   // 256B in shadow memory can be iterated quite fast
 376   static const uptr kMaxOffset = 2048;
 377
 378   uptr left = a1 < a2 ? a1 : a2;
 379   uptr right = a1 < a2 ? a2 : a1;
 380   uptr offset = right - left;
 381   if (offset <= kMaxOffset)
 382     return __asan_region_is_poisoned(left, offset);
 383
 384   AsanThread *t = GetCurrentThread();
 385
 386   // check whether left is a stack memory pointer
 387   if (uptr shadow_offset1 = t->GetStackVariableShadowStart(left)) {
 388     uptr shadow_offset2 = t->GetStackVariableShadowStart(right);
 389     return shadow_offset2 == 0 || shadow_offset1 != shadow_offset2;
 390   }
 391
 392   // check whether left is a heap memory address
 393   HeapAddressDescription hdesc1, hdesc2;
 394   if (GetHeapAddressInformation(left, 0, &hdesc1) &&
 395       hdesc1.chunk_access.access_type == kAccessTypeInside)
 396     return !GetHeapAddressInformation(right, 0, &hdesc2) ||
 397         hdesc2.chunk_access.access_type != kAccessTypeInside ||
 398         hdesc1.chunk_access.chunk_begin != hdesc2.chunk_access.chunk_begin;
 399
 400   // check whether left is an address of a global variable
 401   GlobalAddressDescription gdesc1, gdesc2;
 402   if (GetGlobalAddressInformation(left, 0, &gdesc1))
 403     return !GetGlobalAddressInformation(right - 1, 0, &gdesc2) ||
 404         !gdesc1.PointsInsideTheSameVariable(gdesc2);
 405
 406   if (t->GetStackVariableShadowStart(right) ||
 407       GetHeapAddressInformation(right, 0, &hdesc2) ||
 408       GetGlobalAddressInformation(right - 1, 0, &gdesc2))
 409     return true;
 410
 411   // At this point we know nothing about both a1 and a2 addresses.
 412   return false;
 413 }
 414
 415 static inline void CheckForInvalidPointerPair(void *p1, void *p2) {
 416   switch (flags()->detect_invalid_pointer_pairs) {
 417     case 0:
 418       return;
 419     case 1:
 420       if (p1 == nullptr || p2 == nullptr)
 421         return;
 422       break;
 423   }
 424
 425   uptr a1 = reinterpret_cast<uptr>(p1);
 426   uptr a2 = reinterpret_cast<uptr>(p2);
 427
 428   if (IsInvalidPointerPair(a1, a2)) {
 429     GET_CALLER_PC_BP_SP;
 430     ReportInvalidPointerPair(pc, bp, sp, a1, a2);
 431   }
 432 }
 433 // ----------------------- Mac-specific reports ----------------- {{{1
 434
 435 void ReportMacMzReallocUnknown(uptr addr, uptr zone_ptr, const char *zone_name,
 436                                BufferedStackTrace *stack) {
 437   ScopedInErrorReport in_report;
 438   Printf("mz_realloc(%p) -- attempting to realloc unallocated memory.\n"
 439              "This is an unrecoverable problem, exiting now.\n",
 440              addr);
 441   PrintZoneForPointer(addr, zone_ptr, zone_name);
 442   stack->Print();
 443   DescribeAddressIfHeap(addr);
 444 }
 445
 446 // -------------- SuppressErrorReport -------------- {{{1
 447 // Avoid error reports duplicating for ASan recover mode.
 448 static bool SuppressErrorReport(uptr pc) {
 449   if (!common_flags()->suppress_equal_pcs) return false;
 450   for (unsigned i = 0; i < kAsanBuggyPcPoolSize; i++) {
 451     uptr cmp = atomic_load_relaxed(&AsanBuggyPcPool[i]);
 452     if (cmp == 0 && atomic_compare_exchange_strong(&AsanBuggyPcPool[i], &cmp,
 453                                                    pc, memory_order_relaxed))
 454       return false;
 455     if (cmp == pc) return true;
 456   }
 457   Die();
 458 }
 459
 460 void ReportGenericError(uptr pc, uptr bp, uptr sp, uptr addr, bool is_write,
 461                         uptr access_size, u32 exp, bool fatal) {
 462   if (!fatal && SuppressErrorReport(pc)) return;
 463   ENABLE_FRAME_POINTER;
 464
 465   // Optimization experiments.
 466   // The experiments can be used to evaluate potential optimizations that remove
 467   // instrumentation (assess false negatives). Instead of completely removing
 468   // some instrumentation, compiler can emit special calls into runtime
 469   // (e.g. __asan_report_exp_load1 instead of __asan_report_load1) and pass
 470   // mask of experiments (exp).
 471   // The reaction to a non-zero value of exp is to be defined.
 472   (void)exp;
 473
 474   ScopedInErrorReport in_report(fatal);
 475   ErrorGeneric error(GetCurrentTidOrInvalid(), pc, bp, sp, addr, is_write,
 476                      access_size);
 477   in_report.ReportError(error);
 478 }
 479
 480 }  // namespace __asan
 481
 482 // --------------------------- Interface --------------------- {{{1
 483 using namespace __asan;
 484
 485 void __asan_report_error(uptr pc, uptr bp, uptr sp, uptr addr, int is_write,
 486                          uptr access_size, u32 exp) {
 487   ENABLE_FRAME_POINTER;
 488   bool fatal = flags()->halt_on_error;
 489   ReportGenericError(pc, bp, sp, addr, is_write, access_size, exp, fatal);
 490 }
 491
 492 void NOINLINE __asan_set_error_report_callback(void (*callback)(const char*)) {
 493   BlockingMutexLock l(&error_message_buf_mutex);
 494   error_report_callback = callback;
 495 }
 496
 497 void __asan_describe_address(uptr addr) {
 498   // Thread registry must be locked while we're describing an address.
 499   asanThreadRegistry().Lock();
 500   PrintAddressDescription(addr, 1, "");
 501   asanThreadRegistry().Unlock();
 502 }
 503
 504 int __asan_report_present() {
 505   return ScopedInErrorReport::CurrentError().kind != kErrorKindInvalid;
 506 }
 507
 508 uptr __asan_get_report_pc() {
 509   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 510     return ScopedInErrorReport::CurrentError().Generic.pc;
 511   return 0;
 512 }
 513
 514 uptr __asan_get_report_bp() {
 515   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 516     return ScopedInErrorReport::CurrentError().Generic.bp;
 517   return 0;
 518 }
 519
 520 uptr __asan_get_report_sp() {
 521   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 522     return ScopedInErrorReport::CurrentError().Generic.sp;
 523   return 0;
 524 }
 525
 526 uptr __asan_get_report_address() {
 527   ErrorDescription &err = ScopedInErrorReport::CurrentError();
 528   if (err.kind == kErrorKindGeneric)
 529     return err.Generic.addr_description.Address();
 530   else if (err.kind == kErrorKindDoubleFree)
 531     return err.DoubleFree.addr_description.addr;
 532   return 0;
 533 }
 534
 535 int __asan_get_report_access_type() {
 536   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 537     return ScopedInErrorReport::CurrentError().Generic.is_write;
 538   return 0;
 539 }
 540
 541 uptr __asan_get_report_access_size() {
 542   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 543     return ScopedInErrorReport::CurrentError().Generic.access_size;
 544   return 0;
 545 }
 546
 547 const char *__asan_get_report_description() {
 548   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 549     return ScopedInErrorReport::CurrentError().Generic.bug_descr;
 550   return ScopedInErrorReport::CurrentError().Base.scariness.GetDescription();
 551 }
 552
 553 extern "C" {
 554 SANITIZER_INTERFACE_ATTRIBUTE
 555 void __sanitizer_ptr_sub(void *a, void *b) {
 556   CheckForInvalidPointerPair(a, b);
 557 }
 558 SANITIZER_INTERFACE_ATTRIBUTE
 559 void __sanitizer_ptr_cmp(void *a, void *b) {
 560   CheckForInvalidPointerPair(a, b);
 561 }
 562 } // extern "C"
 563
 564 // Provide default implementation of __asan_on_error that does nothing
 565 // and may be overriden by user.
 566 SANITIZER_INTERFACE_WEAK_DEF(void, __asan_on_error, void) {}