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_report.h"
  15
  16 #include "asan_descriptions.h"
  17 #include "asan_errors.h"
  18 #include "asan_flags.h"
  19 #include "asan_internal.h"
  20 #include "asan_mapping.h"
  21 #include "asan_scariness_score.h"
  22 #include "asan_stack.h"
  23 #include "asan_thread.h"
  24 #include "sanitizer_common/sanitizer_common.h"
  25 #include "sanitizer_common/sanitizer_flags.h"
  26 #include "sanitizer_common/sanitizer_interface_internal.h"
  27 #include "sanitizer_common/sanitizer_report_decorator.h"
  28 #include "sanitizer_common/sanitizer_stackdepot.h"
  29 #include "sanitizer_common/sanitizer_symbolizer.h"
  30
  31 namespace __asan {
  32
  33 // -------------------- User-specified callbacks ----------------- {{{1
  34 static void (*error_report_callback)(const char*);
  35 static char *error_message_buffer = nullptr;
  36 static uptr error_message_buffer_pos = 0;
  37 static Mutex error_message_buf_mutex;
  38 static const unsigned kAsanBuggyPcPoolSize = 25;
  39 static __sanitizer::atomic_uintptr_t AsanBuggyPcPool[kAsanBuggyPcPoolSize];
  40
  41 void AppendToErrorMessageBuffer(const char *buffer) {
  42   Lock l(&error_message_buf_mutex);
  43   if (!error_message_buffer) {
  44     error_message_buffer =
  45       (char*)MmapOrDieQuietly(kErrorMessageBufferSize, __func__);
  46     error_message_buffer_pos = 0;
  47   }
  48   uptr length = internal_strlen(buffer);
  49   RAW_CHECK(kErrorMessageBufferSize >= error_message_buffer_pos);
  50   uptr remaining = kErrorMessageBufferSize - error_message_buffer_pos;
  51   internal_strncpy(error_message_buffer + error_message_buffer_pos,
  52                    buffer, remaining);
  53   error_message_buffer[kErrorMessageBufferSize - 1] = '\0';
  54   // FIXME: reallocate the buffer instead of truncating the message.
  55   error_message_buffer_pos += Min(remaining, length);
  56 }
  57
  58 // ---------------------- Helper functions ----------------------- {{{1
  59
  60 void PrintMemoryByte(InternalScopedString *str, const char *before, u8 byte,
  61                      bool in_shadow, const char *after) {
  62   Decorator d;
  63   str->AppendF("%s%s%x%x%s%s", before,
  64                in_shadow ? d.ShadowByte(byte) : d.MemoryByte(), byte >> 4,
  65                byte & 15, d.Default(), after);
  66 }
  67
  68 static void PrintZoneForPointer(uptr ptr, uptr zone_ptr,
  69                                 const char *zone_name) {
  70   if (zone_ptr) {
  71     if (zone_name) {
  72       Printf("malloc_zone_from_ptr(%p) = %p, which is %s\n", (void *)ptr,
  73              (void *)zone_ptr, zone_name);
  74     } else {
  75       Printf("malloc_zone_from_ptr(%p) = %p, which doesn't have a name\n",
  76              (void *)ptr, (void *)zone_ptr);
  77     }
  78   } else {
  79     Printf("malloc_zone_from_ptr(%p) = 0\n", (void *)ptr);
  80   }
  81 }
  82
  83 // ---------------------- Address Descriptions ------------------- {{{1
  84
  85 bool ParseFrameDescription(const char *frame_descr,
  86                            InternalMmapVector<StackVarDescr> *vars) {
  87   CHECK(frame_descr);
  88   const char *p;
  89   // This string is created by the compiler and has the following form:
  90   // "n alloc_1 alloc_2 ... alloc_n"
  91   // where alloc_i looks like "offset size len ObjectName"
  92   // or                       "offset size len ObjectName:line".
  93   uptr n_objects = (uptr)internal_simple_strtoll(frame_descr, &p, 10);
  94   if (n_objects == 0)
  95     return false;
  96
  97   for (uptr i = 0; i < n_objects; i++) {
  98     uptr beg  = (uptr)internal_simple_strtoll(p, &p, 10);
  99     uptr size = (uptr)internal_simple_strtoll(p, &p, 10);
 100     uptr len  = (uptr)internal_simple_strtoll(p, &p, 10);
 101     if (beg == 0 || size == 0 || *p != ' ') {
 102       return false;
 103     }
 104     p++;
 105     char *colon_pos = internal_strchr(p, ':');
 106     uptr line = 0;
 107     uptr name_len = len;
 108     if (colon_pos != nullptr && colon_pos < p + len) {
 109       name_len = colon_pos - p;
 110       line = (uptr)internal_simple_strtoll(colon_pos + 1, nullptr, 10);
 111     }
 112     StackVarDescr var = {beg, size, p, name_len, line};
 113     vars->push_back(var);
 114     p += len;
 115   }
 116
 117   return true;
 118 }
 119
 120 // -------------------- Different kinds of reports ----------------- {{{1
 121
 122 // Use ScopedInErrorReport to run common actions just before and
 123 // immediately after printing error report.
 124 class ScopedInErrorReport {
 125  public:
 126   explicit ScopedInErrorReport(bool fatal = false)
 127       : halt_on_error_(fatal || flags()->halt_on_error) {
 128     // Make sure the registry and sanitizer report mutexes are locked while
 129     // we're printing an error report.
 130     // We can lock them only here to avoid self-deadlock in case of
 131     // recursive reports.
 132     asanThreadRegistry().Lock();
 133     Printf(
 134         "=================================================================\n");
 135   }
 136
 137   ~ScopedInErrorReport() {
 138     if (halt_on_error_ && !__sanitizer_acquire_crash_state()) {
 139       asanThreadRegistry().Unlock();
 140       return;
 141     }
 142     ASAN_ON_ERROR();
 143     if (current_error_.IsValid()) current_error_.Print();
 144
 145     // Make sure the current thread is announced.
 146     DescribeThread(GetCurrentThread());
 147     // We may want to grab this lock again when printing stats.
 148     asanThreadRegistry().Unlock();
 149     // Print memory stats.
 150     if (flags()->print_stats)
 151       __asan_print_accumulated_stats();
 152
 153     if (common_flags()->print_cmdline)
 154       PrintCmdline();
 155
 156     if (common_flags()->print_module_map == 2)
 157       DumpProcessMap();
 158
 159     // Copy the message buffer so that we could start logging without holding a
 160     // lock that gets acquired during printing.
 161     InternalMmapVector<char> buffer_copy(kErrorMessageBufferSize);
 162     {
 163       Lock l(&error_message_buf_mutex);
 164       internal_memcpy(buffer_copy.data(),
 165                       error_message_buffer, kErrorMessageBufferSize);
 166       // Clear error_message_buffer so that if we find other errors
 167       // we don't re-log this error.
 168       error_message_buffer_pos = 0;
 169     }
 170
 171     LogFullErrorReport(buffer_copy.data());
 172
 173     if (error_report_callback) {
 174       error_report_callback(buffer_copy.data());
 175     }
 176
 177     if (halt_on_error_ && common_flags()->abort_on_error) {
 178       // On Android the message is truncated to 512 characters.
 179       // FIXME: implement "compact" error format, possibly without, or with
 180       // highly compressed stack traces?
 181       // FIXME: or just use the summary line as abort message?
 182       SetAbortMessage(buffer_copy.data());
 183     }
 184
 185     // In halt_on_error = false mode, reset the current error object (before
 186     // unlocking).
 187     if (!halt_on_error_)
 188       internal_memset(&current_error_, 0, sizeof(current_error_));
 189
 190     if (halt_on_error_) {
 191       Report("ABORTING\n");
 192       Die();
 193     }
 194   }
 195
 196   void ReportError(const ErrorDescription &description) {
 197     // Can only report one error per ScopedInErrorReport.
 198     CHECK_EQ(current_error_.kind, kErrorKindInvalid);
 199     internal_memcpy(&current_error_, &description, sizeof(current_error_));
 200   }
 201
 202   static ErrorDescription &CurrentError() {
 203     return current_error_;
 204   }
 205
 206  private:
 207   ScopedErrorReportLock error_report_lock_;
 208   // Error currently being reported. This enables the destructor to interact
 209   // with the debugger and point it to an error description.
 210   static ErrorDescription current_error_;
 211   bool halt_on_error_;
 212 };
 213
 214 ErrorDescription ScopedInErrorReport::current_error_(LINKER_INITIALIZED);
 215
 216 void ReportDeadlySignal(const SignalContext &sig) {
 217   ScopedInErrorReport in_report(/*fatal*/ true);
 218   ErrorDeadlySignal error(GetCurrentTidOrInvalid(), sig);
 219   in_report.ReportError(error);
 220 }
 221
 222 void ReportDoubleFree(uptr addr, BufferedStackTrace *free_stack) {
 223   ScopedInErrorReport in_report;
 224   ErrorDoubleFree error(GetCurrentTidOrInvalid(), free_stack, addr);
 225   in_report.ReportError(error);
 226 }
 227
 228 void ReportNewDeleteTypeMismatch(uptr addr, uptr delete_size,
 229                                  uptr delete_alignment,
 230                                  BufferedStackTrace *free_stack) {
 231   ScopedInErrorReport in_report;
 232   ErrorNewDeleteTypeMismatch error(GetCurrentTidOrInvalid(), free_stack, addr,
 233                                    delete_size, delete_alignment);
 234   in_report.ReportError(error);
 235 }
 236
 237 void ReportFreeNotMalloced(uptr addr, BufferedStackTrace *free_stack) {
 238   ScopedInErrorReport in_report;
 239   ErrorFreeNotMalloced error(GetCurrentTidOrInvalid(), free_stack, addr);
 240   in_report.ReportError(error);
 241 }
 242
 243 void ReportAllocTypeMismatch(uptr addr, BufferedStackTrace *free_stack,
 244                              AllocType alloc_type,
 245                              AllocType dealloc_type) {
 246   ScopedInErrorReport in_report;
 247   ErrorAllocTypeMismatch error(GetCurrentTidOrInvalid(), free_stack, addr,
 248                                alloc_type, dealloc_type);
 249   in_report.ReportError(error);
 250 }
 251
 252 void ReportMallocUsableSizeNotOwned(uptr addr, BufferedStackTrace *stack) {
 253   ScopedInErrorReport in_report;
 254   ErrorMallocUsableSizeNotOwned error(GetCurrentTidOrInvalid(), stack, addr);
 255   in_report.ReportError(error);
 256 }
 257
 258 void ReportSanitizerGetAllocatedSizeNotOwned(uptr addr,
 259                                              BufferedStackTrace *stack) {
 260   ScopedInErrorReport in_report;
 261   ErrorSanitizerGetAllocatedSizeNotOwned error(GetCurrentTidOrInvalid(), stack,
 262                                                addr);
 263   in_report.ReportError(error);
 264 }
 265
 266 void ReportCallocOverflow(uptr count, uptr size, BufferedStackTrace *stack) {
 267   ScopedInErrorReport in_report(/*fatal*/ true);
 268   ErrorCallocOverflow error(GetCurrentTidOrInvalid(), stack, count, size);
 269   in_report.ReportError(error);
 270 }
 271
 272 void ReportReallocArrayOverflow(uptr count, uptr size,
 273                                 BufferedStackTrace *stack) {
 274   ScopedInErrorReport in_report(/*fatal*/ true);
 275   ErrorReallocArrayOverflow error(GetCurrentTidOrInvalid(), stack, count, size);
 276   in_report.ReportError(error);
 277 }
 278
 279 void ReportPvallocOverflow(uptr size, BufferedStackTrace *stack) {
 280   ScopedInErrorReport in_report(/*fatal*/ true);
 281   ErrorPvallocOverflow error(GetCurrentTidOrInvalid(), stack, size);
 282   in_report.ReportError(error);
 283 }
 284
 285 void ReportInvalidAllocationAlignment(uptr alignment,
 286                                       BufferedStackTrace *stack) {
 287   ScopedInErrorReport in_report(/*fatal*/ true);
 288   ErrorInvalidAllocationAlignment error(GetCurrentTidOrInvalid(), stack,
 289                                         alignment);
 290   in_report.ReportError(error);
 291 }
 292
 293 void ReportInvalidAlignedAllocAlignment(uptr size, uptr alignment,
 294                                         BufferedStackTrace *stack) {
 295   ScopedInErrorReport in_report(/*fatal*/ true);
 296   ErrorInvalidAlignedAllocAlignment error(GetCurrentTidOrInvalid(), stack,
 297                                           size, alignment);
 298   in_report.ReportError(error);
 299 }
 300
 301 void ReportInvalidPosixMemalignAlignment(uptr alignment,
 302                                          BufferedStackTrace *stack) {
 303   ScopedInErrorReport in_report(/*fatal*/ true);
 304   ErrorInvalidPosixMemalignAlignment error(GetCurrentTidOrInvalid(), stack,
 305                                            alignment);
 306   in_report.ReportError(error);
 307 }
 308
 309 void ReportAllocationSizeTooBig(uptr user_size, uptr total_size, uptr max_size,
 310                                 BufferedStackTrace *stack) {
 311   ScopedInErrorReport in_report(/*fatal*/ true);
 312   ErrorAllocationSizeTooBig error(GetCurrentTidOrInvalid(), stack, user_size,
 313                                   total_size, max_size);
 314   in_report.ReportError(error);
 315 }
 316
 317 void ReportRssLimitExceeded(BufferedStackTrace *stack) {
 318   ScopedInErrorReport in_report(/*fatal*/ true);
 319   ErrorRssLimitExceeded error(GetCurrentTidOrInvalid(), stack);
 320   in_report.ReportError(error);
 321 }
 322
 323 void ReportOutOfMemory(uptr requested_size, BufferedStackTrace *stack) {
 324   ScopedInErrorReport in_report(/*fatal*/ true);
 325   ErrorOutOfMemory error(GetCurrentTidOrInvalid(), stack, requested_size);
 326   in_report.ReportError(error);
 327 }
 328
 329 void ReportStringFunctionMemoryRangesOverlap(const char *function,
 330                                              const char *offset1, uptr length1,
 331                                              const char *offset2, uptr length2,
 332                                              BufferedStackTrace *stack) {
 333   ScopedInErrorReport in_report;
 334   ErrorStringFunctionMemoryRangesOverlap error(
 335       GetCurrentTidOrInvalid(), stack, (uptr)offset1, length1, (uptr)offset2,
 336       length2, function);
 337   in_report.ReportError(error);
 338 }
 339
 340 void ReportStringFunctionSizeOverflow(uptr offset, uptr size,
 341                                       BufferedStackTrace *stack) {
 342   ScopedInErrorReport in_report;
 343   ErrorStringFunctionSizeOverflow error(GetCurrentTidOrInvalid(), stack, offset,
 344                                         size);
 345   in_report.ReportError(error);
 346 }
 347
 348 void ReportBadParamsToAnnotateContiguousContainer(uptr beg, uptr end,
 349                                                   uptr old_mid, uptr new_mid,
 350                                                   BufferedStackTrace *stack) {
 351   ScopedInErrorReport in_report;
 352   ErrorBadParamsToAnnotateContiguousContainer error(
 353       GetCurrentTidOrInvalid(), stack, beg, end, old_mid, new_mid);
 354   in_report.ReportError(error);
 355 }
 356
 357 void ReportBadParamsToAnnotateDoubleEndedContiguousContainer(
 358     uptr storage_beg, uptr storage_end, uptr old_container_beg,
 359     uptr old_container_end, uptr new_container_beg, uptr new_container_end,
 360     BufferedStackTrace *stack) {
 361   ScopedInErrorReport in_report;
 362   ErrorBadParamsToAnnotateDoubleEndedContiguousContainer error(
 363       GetCurrentTidOrInvalid(), stack, storage_beg, storage_end,
 364       old_container_beg, old_container_end, new_container_beg,
 365       new_container_end);
 366   in_report.ReportError(error);
 367 }
 368
 369 void ReportODRViolation(const __asan_global *g1, u32 stack_id1,
 370                         const __asan_global *g2, u32 stack_id2) {
 371   ScopedInErrorReport in_report;
 372   ErrorODRViolation error(GetCurrentTidOrInvalid(), g1, stack_id1, g2,
 373                           stack_id2);
 374   in_report.ReportError(error);
 375 }
 376
 377 // ----------------------- CheckForInvalidPointerPair ----------- {{{1
 378 static NOINLINE void ReportInvalidPointerPair(uptr pc, uptr bp, uptr sp,
 379                                               uptr a1, uptr a2) {
 380   ScopedInErrorReport in_report;
 381   ErrorInvalidPointerPair error(GetCurrentTidOrInvalid(), pc, bp, sp, a1, a2);
 382   in_report.ReportError(error);
 383 }
 384
 385 static bool IsInvalidPointerPair(uptr a1, uptr a2) {
 386   if (a1 == a2)
 387     return false;
 388
 389   // 256B in shadow memory can be iterated quite fast
 390   static const uptr kMaxOffset = 2048;
 391
 392   uptr left = a1 < a2 ? a1 : a2;
 393   uptr right = a1 < a2 ? a2 : a1;
 394   uptr offset = right - left;
 395   if (offset <= kMaxOffset)
 396     return __asan_region_is_poisoned(left, offset);
 397
 398   AsanThread *t = GetCurrentThread();
 399
 400   // check whether left is a stack memory pointer
 401   if (uptr shadow_offset1 = t->GetStackVariableShadowStart(left)) {
 402     uptr shadow_offset2 = t->GetStackVariableShadowStart(right);
 403     return shadow_offset2 == 0 || shadow_offset1 != shadow_offset2;
 404   }
 405
 406   // check whether left is a heap memory address
 407   HeapAddressDescription hdesc1, hdesc2;
 408   if (GetHeapAddressInformation(left, 0, &hdesc1) &&
 409       hdesc1.chunk_access.access_type == kAccessTypeInside)
 410     return !GetHeapAddressInformation(right, 0, &hdesc2) ||
 411         hdesc2.chunk_access.access_type != kAccessTypeInside ||
 412         hdesc1.chunk_access.chunk_begin != hdesc2.chunk_access.chunk_begin;
 413
 414   // check whether left is an address of a global variable
 415   GlobalAddressDescription gdesc1, gdesc2;
 416   if (GetGlobalAddressInformation(left, 0, &gdesc1))
 417     return !GetGlobalAddressInformation(right - 1, 0, &gdesc2) ||
 418         !gdesc1.PointsInsideTheSameVariable(gdesc2);
 419
 420   if (t->GetStackVariableShadowStart(right) ||
 421       GetHeapAddressInformation(right, 0, &hdesc2) ||
 422       GetGlobalAddressInformation(right - 1, 0, &gdesc2))
 423     return true;
 424
 425   // At this point we know nothing about both a1 and a2 addresses.
 426   return false;
 427 }
 428
 429 static inline void CheckForInvalidPointerPair(void *p1, void *p2) {
 430   switch (flags()->detect_invalid_pointer_pairs) {
 431     case 0:
 432       return;
 433     case 1:
 434       if (p1 == nullptr || p2 == nullptr)
 435         return;
 436       break;
 437   }
 438
 439   uptr a1 = reinterpret_cast<uptr>(p1);
 440   uptr a2 = reinterpret_cast<uptr>(p2);
 441
 442   if (IsInvalidPointerPair(a1, a2)) {
 443     GET_CALLER_PC_BP_SP;
 444     ReportInvalidPointerPair(pc, bp, sp, a1, a2);
 445   }
 446 }
 447 // ----------------------- Mac-specific reports ----------------- {{{1
 448
 449 void ReportMacMzReallocUnknown(uptr addr, uptr zone_ptr, const char *zone_name,
 450                                BufferedStackTrace *stack) {
 451   ScopedInErrorReport in_report;
 452   Printf(
 453       "mz_realloc(%p) -- attempting to realloc unallocated memory.\n"
 454       "This is an unrecoverable problem, exiting now.\n",
 455       (void *)addr);
 456   PrintZoneForPointer(addr, zone_ptr, zone_name);
 457   stack->Print();
 458   DescribeAddressIfHeap(addr);
 459 }
 460
 461 // -------------- SuppressErrorReport -------------- {{{1
 462 // Avoid error reports duplicating for ASan recover mode.
 463 static bool SuppressErrorReport(uptr pc) {
 464   if (!common_flags()->suppress_equal_pcs) return false;
 465   for (unsigned i = 0; i < kAsanBuggyPcPoolSize; i++) {
 466     uptr cmp = atomic_load_relaxed(&AsanBuggyPcPool[i]);
 467     if (cmp == 0 && atomic_compare_exchange_strong(&AsanBuggyPcPool[i], &cmp,
 468                                                    pc, memory_order_relaxed))
 469       return false;
 470     if (cmp == pc) return true;
 471   }
 472   Die();
 473 }
 474
 475 void ReportGenericError(uptr pc, uptr bp, uptr sp, uptr addr, bool is_write,
 476                         uptr access_size, u32 exp, bool fatal) {
 477   if (__asan_test_only_reported_buggy_pointer) {
 478     *__asan_test_only_reported_buggy_pointer = addr;
 479     return;
 480   }
 481   if (!fatal && SuppressErrorReport(pc)) return;
 482   ENABLE_FRAME_POINTER;
 483
 484   // Optimization experiments.
 485   // The experiments can be used to evaluate potential optimizations that remove
 486   // instrumentation (assess false negatives). Instead of completely removing
 487   // some instrumentation, compiler can emit special calls into runtime
 488   // (e.g. __asan_report_exp_load1 instead of __asan_report_load1) and pass
 489   // mask of experiments (exp).
 490   // The reaction to a non-zero value of exp is to be defined.
 491   (void)exp;
 492
 493   ScopedInErrorReport in_report(fatal);
 494   ErrorGeneric error(GetCurrentTidOrInvalid(), pc, bp, sp, addr, is_write,
 495                      access_size);
 496   in_report.ReportError(error);
 497 }
 498
 499 }  // namespace __asan
 500
 501 // --------------------------- Interface --------------------- {{{1
 502 using namespace __asan;
 503
 504 void __asan_report_error(uptr pc, uptr bp, uptr sp, uptr addr, int is_write,
 505                          uptr access_size, u32 exp) {
 506   ENABLE_FRAME_POINTER;
 507   bool fatal = flags()->halt_on_error;
 508   ReportGenericError(pc, bp, sp, addr, is_write, access_size, exp, fatal);
 509 }
 510
 511 void NOINLINE __asan_set_error_report_callback(void (*callback)(const char*)) {
 512   Lock l(&error_message_buf_mutex);
 513   error_report_callback = callback;
 514 }
 515
 516 void __asan_describe_address(uptr addr) {
 517   // Thread registry must be locked while we're describing an address.
 518   asanThreadRegistry().Lock();
 519   PrintAddressDescription(addr, 1, "");
 520   asanThreadRegistry().Unlock();
 521 }
 522
 523 int __asan_report_present() {
 524   return ScopedInErrorReport::CurrentError().kind != kErrorKindInvalid;
 525 }
 526
 527 uptr __asan_get_report_pc() {
 528   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 529     return ScopedInErrorReport::CurrentError().Generic.pc;
 530   return 0;
 531 }
 532
 533 uptr __asan_get_report_bp() {
 534   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 535     return ScopedInErrorReport::CurrentError().Generic.bp;
 536   return 0;
 537 }
 538
 539 uptr __asan_get_report_sp() {
 540   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 541     return ScopedInErrorReport::CurrentError().Generic.sp;
 542   return 0;
 543 }
 544
 545 uptr __asan_get_report_address() {
 546   ErrorDescription &err = ScopedInErrorReport::CurrentError();
 547   if (err.kind == kErrorKindGeneric)
 548     return err.Generic.addr_description.Address();
 549   else if (err.kind == kErrorKindDoubleFree)
 550     return err.DoubleFree.addr_description.addr;
 551   return 0;
 552 }
 553
 554 int __asan_get_report_access_type() {
 555   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 556     return ScopedInErrorReport::CurrentError().Generic.is_write;
 557   return 0;
 558 }
 559
 560 uptr __asan_get_report_access_size() {
 561   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 562     return ScopedInErrorReport::CurrentError().Generic.access_size;
 563   return 0;
 564 }
 565
 566 const char *__asan_get_report_description() {
 567   if (ScopedInErrorReport::CurrentError().kind == kErrorKindGeneric)
 568     return ScopedInErrorReport::CurrentError().Generic.bug_descr;
 569   return ScopedInErrorReport::CurrentError().Base.scariness.GetDescription();
 570 }
 571
 572 extern "C" {
 573 SANITIZER_INTERFACE_ATTRIBUTE
 574 void __sanitizer_ptr_sub(void *a, void *b) {
 575   CheckForInvalidPointerPair(a, b);
 576 }
 577 SANITIZER_INTERFACE_ATTRIBUTE
 578 void __sanitizer_ptr_cmp(void *a, void *b) {
 579   CheckForInvalidPointerPair(a, b);
 580 }
 581 } // extern "C"
 582
 583 // Provide default implementation of __asan_on_error that does nothing
 584 // and may be overriden by user.
 585 SANITIZER_INTERFACE_WEAK_DEF(void, __asan_on_error, void) {}