libsanitizer: add hwasan.

Introduce the libhwasan library from LLVM sources.

1 files changed, 651 insertions, 0 deletions

diff --git a/libsanitizer/hwasan/hwasan_report.cpp b/libsanitizer/hwasan/hwasan_report.cpp
new file mode 100644
index 00000000000..0be7deeaee1
--- /dev/null
+++ b/libsanitizer/hwasan/hwasan_report.cpp
@@ -0,0 +1,651 @@
+//===-- hwasan_report.cpp -------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of HWAddressSanitizer.
+//
+// Error reporting.
+//===----------------------------------------------------------------------===//
+
+#include "hwasan_report.h"
+
+#include <dlfcn.h>
+
+#include "hwasan.h"
+#include "hwasan_allocator.h"
+#include "hwasan_globals.h"
+#include "hwasan_mapping.h"
+#include "hwasan_thread.h"
+#include "hwasan_thread_list.h"
+#include "sanitizer_common/sanitizer_allocator_internal.h"
+#include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_flags.h"
+#include "sanitizer_common/sanitizer_mutex.h"
+#include "sanitizer_common/sanitizer_report_decorator.h"
+#include "sanitizer_common/sanitizer_stackdepot.h"
+#include "sanitizer_common/sanitizer_stacktrace_printer.h"
+#include "sanitizer_common/sanitizer_symbolizer.h"
+
+using namespace __sanitizer;
+
+namespace __hwasan {
+
+class ScopedReport {
+ public:
+  ScopedReport(bool fatal = false) : error_message_(1), fatal(fatal) {
+    BlockingMutexLock lock(&error_message_lock_);
+    error_message_ptr_ = fatal ? &error_message_ : nullptr;
+    ++hwasan_report_count;
+  }
+
+  ~ScopedReport() {
+    {
+      BlockingMutexLock lock(&error_message_lock_);
+      if (fatal)
+        SetAbortMessage(error_message_.data());
+      error_message_ptr_ = nullptr;
+    }
+    if (common_flags()->print_module_map >= 2 ||
+        (fatal && common_flags()->print_module_map))
+      DumpProcessMap();
+    if (fatal)
+      Die();
+  }
+
+  static void MaybeAppendToErrorMessage(const char *msg) {
+    BlockingMutexLock lock(&error_message_lock_);
+    if (!error_message_ptr_)
+      return;
+    uptr len = internal_strlen(msg);
+    uptr old_size = error_message_ptr_->size();
+    error_message_ptr_->resize(old_size + len);
+    // overwrite old trailing '\0', keep new trailing '\0' untouched.
+    internal_memcpy(&(*error_message_ptr_)[old_size - 1], msg, len);
+  }
+ private:
+  ScopedErrorReportLock error_report_lock_;
+  InternalMmapVector<char> error_message_;
+  bool fatal;
+
+  static InternalMmapVector<char> *error_message_ptr_;
+  static BlockingMutex error_message_lock_;
+};
+
+InternalMmapVector<char> *ScopedReport::error_message_ptr_;
+BlockingMutex ScopedReport::error_message_lock_;
+
+// If there is an active ScopedReport, append to its error message.
+void AppendToErrorMessageBuffer(const char *buffer) {
+  ScopedReport::MaybeAppendToErrorMessage(buffer);
+}
+
+static StackTrace GetStackTraceFromId(u32 id) {
+  CHECK(id);
+  StackTrace res = StackDepotGet(id);
+  CHECK(res.trace);
+  return res;
+}
+
+// A RAII object that holds a copy of the current thread stack ring buffer.
+// The actual stack buffer may change while we are iterating over it (for
+// example, Printf may call syslog() which can itself be built with hwasan).
+class SavedStackAllocations {
+ public:
+  SavedStackAllocations(StackAllocationsRingBuffer *rb) {
+    uptr size = rb->size() * sizeof(uptr);
+    void *storage =
+        MmapAlignedOrDieOnFatalError(size, size * 2, "saved stack allocations");
+    new (&rb_) StackAllocationsRingBuffer(*rb, storage);
+  }
+
+  ~SavedStackAllocations() {
+    StackAllocationsRingBuffer *rb = get();
+    UnmapOrDie(rb->StartOfStorage(), rb->size() * sizeof(uptr));
+  }
+
+  StackAllocationsRingBuffer *get() {
+    return (StackAllocationsRingBuffer *)&rb_;
+  }
+
+ private:
+  uptr rb_;
+};
+
+class Decorator: public __sanitizer::SanitizerCommonDecorator {
+ public:
+  Decorator() : SanitizerCommonDecorator() { }
+  const char *Access() { return Blue(); }
+  const char *Allocation() const { return Magenta(); }
+  const char *Origin() const { return Magenta(); }
+  const char *Name() const { return Green(); }
+  const char *Location() { return Green(); }
+  const char *Thread() { return Green(); }
+};
+
+static bool FindHeapAllocation(HeapAllocationsRingBuffer *rb, uptr tagged_addr,
+                               HeapAllocationRecord *har, uptr *ring_index,
+                               uptr *num_matching_addrs,
+                               uptr *num_matching_addrs_4b) {
+  if (!rb) return false;
+
+  *num_matching_addrs = 0;
+  *num_matching_addrs_4b = 0;
+  for (uptr i = 0, size = rb->size(); i < size; i++) {
+    auto h = (*rb)[i];
+    if (h.tagged_addr <= tagged_addr &&
+        h.tagged_addr + h.requested_size > tagged_addr) {
+      *har = h;
+      *ring_index = i;
+      return true;
+    }
+
+    // Measure the number of heap ring buffer entries that would have matched
+    // if we had only one entry per address (e.g. if the ring buffer data was
+    // stored at the address itself). This will help us tune the allocator
+    // implementation for MTE.
+    if (UntagAddr(h.tagged_addr) <= UntagAddr(tagged_addr) &&
+        UntagAddr(h.tagged_addr) + h.requested_size > UntagAddr(tagged_addr)) {
+      ++*num_matching_addrs;
+    }
+
+    // Measure the number of heap ring buffer entries that would have matched
+    // if we only had 4 tag bits, which is the case for MTE.
+    auto untag_4b = [](uptr p) {
+      return p & ((1ULL << 60) - 1);
+    };
+    if (untag_4b(h.tagged_addr) <= untag_4b(tagged_addr) &&
+        untag_4b(h.tagged_addr) + h.requested_size > untag_4b(tagged_addr)) {
+      ++*num_matching_addrs_4b;
+    }
+  }
+  return false;
+}
+
+static void PrintStackAllocations(StackAllocationsRingBuffer *sa,
+                                  tag_t addr_tag, uptr untagged_addr) {
+  uptr frames = Min((uptr)flags()->stack_history_size, sa->size());
+  bool found_local = false;
+  for (uptr i = 0; i < frames; i++) {
+    const uptr *record_addr = &(*sa)[i];
+    uptr record = *record_addr;
+    if (!record)
+      break;
+    tag_t base_tag =
+        reinterpret_cast<uptr>(record_addr) >> kRecordAddrBaseTagShift;
+    uptr fp = (record >> kRecordFPShift) << kRecordFPLShift;
+    uptr pc_mask = (1ULL << kRecordFPShift) - 1;
+    uptr pc = record & pc_mask;
+    FrameInfo frame;
+    if (Symbolizer::GetOrInit()->SymbolizeFrame(pc, &frame)) {
+      for (LocalInfo &local : frame.locals) {
+        if (!local.has_frame_offset || !local.has_size || !local.has_tag_offset)
+          continue;
+        tag_t obj_tag = base_tag ^ local.tag_offset;
+        if (obj_tag != addr_tag)
+          continue;
+        // Calculate the offset from the object address to the faulting
+        // address. Because we only store bits 4-19 of FP (bits 0-3 are
+        // guaranteed to be zero), the calculation is performed mod 2^20 and may
+        // harmlessly underflow if the address mod 2^20 is below the object
+        // address.
+        uptr obj_offset =
+            (untagged_addr - fp - local.frame_offset) & (kRecordFPModulus - 1);
+        if (obj_offset >= local.size)
+          continue;
+        if (!found_local) {
+          Printf("Potentially referenced stack objects:\n");
+          found_local = true;
+        }
+        Printf("  %s in %s %s:%d\n", local.name, local.function_name,
+               local.decl_file, local.decl_line);
+      }
+      frame.Clear();
+    }
+  }
+
+  if (found_local)
+    return;
+
+  // We didn't find any locals. Most likely we don't have symbols, so dump
+  // the information that we have for offline analysis.
+  InternalScopedString frame_desc(GetPageSizeCached() * 2);
+  Printf("Previously allocated frames:\n");
+  for (uptr i = 0; i < frames; i++) {
+    const uptr *record_addr = &(*sa)[i];
+    uptr record = *record_addr;
+    if (!record)
+      break;
+    uptr pc_mask = (1ULL << 48) - 1;
+    uptr pc = record & pc_mask;
+    frame_desc.append("  record_addr:0x%zx record:0x%zx",
+                      reinterpret_cast<uptr>(record_addr), record);
+    if (SymbolizedStack *frame = Symbolizer::GetOrInit()->SymbolizePC(pc)) {
+      RenderFrame(&frame_desc, " %F %L\n", 0, frame->info.address, &frame->info,
+                  common_flags()->symbolize_vs_style,
+                  common_flags()->strip_path_prefix);
+      frame->ClearAll();
+    }
+    Printf("%s", frame_desc.data());
+    frame_desc.clear();
+  }
+}
+
+// Returns true if tag == *tag_ptr, reading tags from short granules if
+// necessary. This may return a false positive if tags 1-15 are used as a
+// regular tag rather than a short granule marker.
+static bool TagsEqual(tag_t tag, tag_t *tag_ptr) {
+  if (tag == *tag_ptr)
+    return true;
+  if (*tag_ptr == 0 || *tag_ptr > kShadowAlignment - 1)
+    return false;
+  uptr mem = ShadowToMem(reinterpret_cast<uptr>(tag_ptr));
+  tag_t inline_tag = *reinterpret_cast<tag_t *>(mem + kShadowAlignment - 1);
+  return tag == inline_tag;
+}
+
+// HWASan globals store the size of the global in the descriptor. In cases where
+// we don't have a binary with symbols, we can't grab the size of the global
+// from the debug info - but we might be able to retrieve it from the
+// descriptor. Returns zero if the lookup failed.
+static uptr GetGlobalSizeFromDescriptor(uptr ptr) {
+  // Find the ELF object that this global resides in.
+  Dl_info info;
+  dladdr(reinterpret_cast<void *>(ptr), &info);
+  auto *ehdr = reinterpret_cast<const ElfW(Ehdr) *>(info.dli_fbase);
+  auto *phdr_begin = reinterpret_cast<const ElfW(Phdr) *>(
+      reinterpret_cast<const u8 *>(ehdr) + ehdr->e_phoff);
+
+  // Get the load bias. This is normally the same as the dli_fbase address on
+  // position-independent code, but can be different on non-PIE executables,
+  // binaries using LLD's partitioning feature, or binaries compiled with a
+  // linker script.
+  ElfW(Addr) load_bias = 0;
+  for (const auto &phdr :
+       ArrayRef<const ElfW(Phdr)>(phdr_begin, phdr_begin + ehdr->e_phnum)) {
+    if (phdr.p_type != PT_LOAD || phdr.p_offset != 0)
+      continue;
+    load_bias = reinterpret_cast<ElfW(Addr)>(ehdr) - phdr.p_vaddr;
+    break;
+  }
+
+  // Walk all globals in this ELF object, looking for the one we're interested
+  // in. Once we find it, we can stop iterating and return the size of the
+  // global we're interested in.
+  for (const hwasan_global &global :
+       HwasanGlobalsFor(load_bias, phdr_begin, ehdr->e_phnum))
+    if (global.addr() <= ptr && ptr < global.addr() + global.size())
+      return global.size();
+
+  return 0;
+}
+
+void PrintAddressDescription(
+    uptr tagged_addr, uptr access_size,
+    StackAllocationsRingBuffer *current_stack_allocations) {
+  Decorator d;
+  int num_descriptions_printed = 0;
+  uptr untagged_addr = UntagAddr(tagged_addr);
+
+  // Print some very basic information about the address, if it's a heap.
+  HwasanChunkView chunk = FindHeapChunkByAddress(untagged_addr);
+  if (uptr beg = chunk.Beg()) {
+    uptr size = chunk.ActualSize();
+    Printf("%s[%p,%p) is a %s %s heap chunk; "
+           "size: %zd offset: %zd\n%s",
+           d.Location(),
+           beg, beg + size,
+           chunk.FromSmallHeap() ? "small" : "large",
+           chunk.IsAllocated() ? "allocated" : "unallocated",
+           size, untagged_addr - beg,
+           d.Default());
+  }
+
+  // Check if this looks like a heap buffer overflow by scanning
+  // the shadow left and right and looking for the first adjacent
+  // object with a different memory tag. If that tag matches addr_tag,
+  // check the allocator if it has a live chunk there.
+  tag_t addr_tag = GetTagFromPointer(tagged_addr);
+  tag_t *tag_ptr = reinterpret_cast<tag_t*>(MemToShadow(untagged_addr));
+  tag_t *candidate = nullptr, *left = tag_ptr, *right = tag_ptr;
+  for (int i = 0; i < 1000; i++) {
+    if (TagsEqual(addr_tag, left)) {
+      candidate = left;
+      break;
+    }
+    --left;
+    if (TagsEqual(addr_tag, right)) {
+      candidate = right;
+      break;
+    }
+    ++right;
+  }
+
+  if (candidate) {
+    uptr mem = ShadowToMem(reinterpret_cast<uptr>(candidate));
+    HwasanChunkView chunk = FindHeapChunkByAddress(mem);
+    if (chunk.IsAllocated()) {
+      Printf("%s", d.Location());
+      Printf("%p is located %zd bytes to the %s of %zd-byte region [%p,%p)\n",
+             untagged_addr,
+             candidate == left ? untagged_addr - chunk.End()
+                               : chunk.Beg() - untagged_addr,
+             candidate == left ? "right" : "left", chunk.UsedSize(),
+             chunk.Beg(), chunk.End());
+      Printf("%s", d.Allocation());
+      Printf("allocated here:\n");
+      Printf("%s", d.Default());
+      GetStackTraceFromId(chunk.GetAllocStackId()).Print();
+      num_descriptions_printed++;
+    } else {
+      // Check whether the address points into a loaded library. If so, this is
+      // most likely a global variable.
+      const char *module_name;
+      uptr module_address;
+      Symbolizer *sym = Symbolizer::GetOrInit();
+      if (sym->GetModuleNameAndOffsetForPC(mem, &module_name,
+                                           &module_address)) {
+        DataInfo info;
+        if (sym->SymbolizeData(mem, &info) && info.start) {
+          Printf(
+              "%p is located %zd bytes to the %s of %zd-byte global variable "
+              "%s [%p,%p) in %s\n",
+              untagged_addr,
+              candidate == left ? untagged_addr - (info.start + info.size)
+                                : info.start - untagged_addr,
+              candidate == left ? "right" : "left", info.size, info.name,
+              info.start, info.start + info.size, module_name);
+        } else {
+          uptr size = GetGlobalSizeFromDescriptor(mem);
+          if (size == 0)
+            // We couldn't find the size of the global from the descriptors.
+            Printf(
+                "%p is located to the %s of a global variable in (%s+0x%x)\n",
+                untagged_addr, candidate == left ? "right" : "left",
+                module_name, module_address);
+          else
+            Printf(
+                "%p is located to the %s of a %zd-byte global variable in "
+                "(%s+0x%x)\n",
+                untagged_addr, candidate == left ? "right" : "left", size,
+                module_name, module_address);
+        }
+        num_descriptions_printed++;
+      }
+    }
+  }
+
+  hwasanThreadList().VisitAllLiveThreads([&](Thread *t) {
+    // Scan all threads' ring buffers to find if it's a heap-use-after-free.
+    HeapAllocationRecord har;
+    uptr ring_index, num_matching_addrs, num_matching_addrs_4b;
+    if (FindHeapAllocation(t->heap_allocations(), tagged_addr, &har,
+                           &ring_index, &num_matching_addrs,
+                           &num_matching_addrs_4b)) {
+      Printf("%s", d.Location());
+      Printf("%p is located %zd bytes inside of %zd-byte region [%p,%p)\n",
+             untagged_addr, untagged_addr - UntagAddr(har.tagged_addr),
+             har.requested_size, UntagAddr(har.tagged_addr),
+             UntagAddr(har.tagged_addr) + har.requested_size);
+      Printf("%s", d.Allocation());
+      Printf("freed by thread T%zd here:\n", t->unique_id());
+      Printf("%s", d.Default());
+      GetStackTraceFromId(har.free_context_id).Print();
+
+      Printf("%s", d.Allocation());
+      Printf("previously allocated here:\n", t);
+      Printf("%s", d.Default());
+      GetStackTraceFromId(har.alloc_context_id).Print();
+
+      // Print a developer note: the index of this heap object
+      // in the thread's deallocation ring buffer.
+      Printf("hwasan_dev_note_heap_rb_distance: %zd %zd\n", ring_index + 1,
+             flags()->heap_history_size);
+      Printf("hwasan_dev_note_num_matching_addrs: %zd\n", num_matching_addrs);
+      Printf("hwasan_dev_note_num_matching_addrs_4b: %zd\n",
+             num_matching_addrs_4b);
+
+      t->Announce();
+      num_descriptions_printed++;
+    }
+
+    // Very basic check for stack memory.
+    if (t->AddrIsInStack(untagged_addr)) {
+      Printf("%s", d.Location());
+      Printf("Address %p is located in stack of thread T%zd\n", untagged_addr,
+             t->unique_id());
+      Printf("%s", d.Default());
+      t->Announce();
+
+      auto *sa = (t == GetCurrentThread() && current_stack_allocations)
+                     ? current_stack_allocations
+                     : t->stack_allocations();
+      PrintStackAllocations(sa, addr_tag, untagged_addr);
+      num_descriptions_printed++;
+    }
+  });
+
+  // Print the remaining threads, as an extra information, 1 line per thread.
+  hwasanThreadList().VisitAllLiveThreads([&](Thread *t) { t->Announce(); });
+
+  if (!num_descriptions_printed)
+    // We exhausted our possibilities. Bail out.
+    Printf("HWAddressSanitizer can not describe address in more detail.\n");
+}
+
+void ReportStats() {}
+
+static void PrintTagInfoAroundAddr(tag_t *tag_ptr, uptr num_rows,
+                                   void (*print_tag)(InternalScopedString &s,
+                                                     tag_t *tag)) {
+  const uptr row_len = 16;  // better be power of two.
+  tag_t *center_row_beg = reinterpret_cast<tag_t *>(
+      RoundDownTo(reinterpret_cast<uptr>(tag_ptr), row_len));
+  tag_t *beg_row = center_row_beg - row_len * (num_rows / 2);
+  tag_t *end_row = center_row_beg + row_len * ((num_rows + 1) / 2);
+  InternalScopedString s(GetPageSizeCached() * 8);
+  for (tag_t *row = beg_row; row < end_row; row += row_len) {
+    s.append("%s", row == center_row_beg ? "=>" : "  ");
+    s.append("%p:", row);
+    for (uptr i = 0; i < row_len; i++) {
+      s.append("%s", row + i == tag_ptr ? "[" : " ");
+      print_tag(s, &row[i]);
+      s.append("%s", row + i == tag_ptr ? "]" : " ");
+    }
+    s.append("\n");
+  }
+  Printf("%s", s.data());
+}
+
+static void PrintTagsAroundAddr(tag_t *tag_ptr) {
+  Printf(
+      "Memory tags around the buggy address (one tag corresponds to %zd "
+      "bytes):\n", kShadowAlignment);
+  PrintTagInfoAroundAddr(tag_ptr, 17, [](InternalScopedString &s, tag_t *tag) {
+    s.append("%02x", *tag);
+  });
+
+  Printf(
+      "Tags for short granules around the buggy address (one tag corresponds "
+      "to %zd bytes):\n",
+      kShadowAlignment);
+  PrintTagInfoAroundAddr(tag_ptr, 3, [](InternalScopedString &s, tag_t *tag) {
+    if (*tag >= 1 && *tag <= kShadowAlignment) {
+      uptr granule_addr = ShadowToMem(reinterpret_cast<uptr>(tag));
+      s.append("%02x",
+               *reinterpret_cast<u8 *>(granule_addr + kShadowAlignment - 1));
+    } else {
+      s.append("..");
+    }
+  });
+  Printf(
+      "See "
+      "https://clang.llvm.org/docs/"
+      "HardwareAssistedAddressSanitizerDesign.html#short-granules for a "
+      "description of short granule tags\n");
+}
+
+void ReportInvalidFree(StackTrace *stack, uptr tagged_addr) {
+  ScopedReport R(flags()->halt_on_error);
+
+  uptr untagged_addr = UntagAddr(tagged_addr);
+  tag_t ptr_tag = GetTagFromPointer(tagged_addr);
+  tag_t *tag_ptr = reinterpret_cast<tag_t*>(MemToShadow(untagged_addr));
+  tag_t mem_tag = *tag_ptr;
+  Decorator d;
+  Printf("%s", d.Error());
+  uptr pc = stack->size ? stack->trace[0] : 0;
+  const char *bug_type = "invalid-free";
+  Report("ERROR: %s: %s on address %p at pc %p\n", SanitizerToolName, bug_type,
+         untagged_addr, pc);
+  Printf("%s", d.Access());
+  Printf("tags: %02x/%02x (ptr/mem)\n", ptr_tag, mem_tag);
+  Printf("%s", d.Default());
+
+  stack->Print();
+
+  PrintAddressDescription(tagged_addr, 0, nullptr);
+
+  PrintTagsAroundAddr(tag_ptr);
+
+  ReportErrorSummary(bug_type, stack);
+}
+
+void ReportTailOverwritten(StackTrace *stack, uptr tagged_addr, uptr orig_size,
+                           const u8 *expected) {
+  uptr tail_size = kShadowAlignment - (orig_size % kShadowAlignment);
+  ScopedReport R(flags()->halt_on_error);
+  Decorator d;
+  uptr untagged_addr = UntagAddr(tagged_addr);
+  Printf("%s", d.Error());
+  const char *bug_type = "allocation-tail-overwritten";
+  Report("ERROR: %s: %s; heap object [%p,%p) of size %zd\n", SanitizerToolName,
+         bug_type, untagged_addr, untagged_addr + orig_size, orig_size);
+  Printf("\n%s", d.Default());
+  stack->Print();
+  HwasanChunkView chunk = FindHeapChunkByAddress(untagged_addr);
+  if (chunk.Beg()) {
+    Printf("%s", d.Allocation());
+    Printf("allocated here:\n");
+    Printf("%s", d.Default());
+    GetStackTraceFromId(chunk.GetAllocStackId()).Print();
+  }
+
+  InternalScopedString s(GetPageSizeCached() * 8);
+  CHECK_GT(tail_size, 0U);
+  CHECK_LT(tail_size, kShadowAlignment);
+  u8 *tail = reinterpret_cast<u8*>(untagged_addr + orig_size);
+  s.append("Tail contains: ");
+  for (uptr i = 0; i < kShadowAlignment - tail_size; i++)
+    s.append(".. ");
+  for (uptr i = 0; i < tail_size; i++)
+    s.append("%02x ", tail[i]);
+  s.append("\n");
+  s.append("Expected:      ");
+  for (uptr i = 0; i < kShadowAlignment - tail_size; i++)
+    s.append(".. ");
+  for (uptr i = 0; i < tail_size; i++)
+    s.append("%02x ", expected[i]);
+  s.append("\n");
+  s.append("               ");
+  for (uptr i = 0; i < kShadowAlignment - tail_size; i++)
+    s.append("   ");
+  for (uptr i = 0; i < tail_size; i++)
+    s.append("%s ", expected[i] != tail[i] ? "^^" : "  ");
+
+  s.append("\nThis error occurs when a buffer overflow overwrites memory\n"
+    "to the right of a heap object, but within the %zd-byte granule, e.g.\n"
+    "   char *x = new char[20];\n"
+    "   x[25] = 42;\n"
+    "%s does not detect such bugs in uninstrumented code at the time of write,"
+    "\nbut can detect them at the time of free/delete.\n"
+    "To disable this feature set HWASAN_OPTIONS=free_checks_tail_magic=0\n",
+    kShadowAlignment, SanitizerToolName);
+  Printf("%s", s.data());
+  GetCurrentThread()->Announce();
+
+  tag_t *tag_ptr = reinterpret_cast<tag_t*>(MemToShadow(untagged_addr));
+  PrintTagsAroundAddr(tag_ptr);
+
+  ReportErrorSummary(bug_type, stack);
+}
+
+void ReportTagMismatch(StackTrace *stack, uptr tagged_addr, uptr access_size,
+                       bool is_store, bool fatal, uptr *registers_frame) {
+  ScopedReport R(fatal);
+  SavedStackAllocations current_stack_allocations(
+      GetCurrentThread()->stack_allocations());
+
+  Decorator d;
+  Printf("%s", d.Error());
+  uptr untagged_addr = UntagAddr(tagged_addr);
+  // TODO: when possible, try to print heap-use-after-free, etc.
+  const char *bug_type = "tag-mismatch";
+  uptr pc = stack->size ? stack->trace[0] : 0;
+  Report("ERROR: %s: %s on address %p at pc %p\n", SanitizerToolName, bug_type,
+         untagged_addr, pc);
+
+  Thread *t = GetCurrentThread();
+
+  sptr offset =
+      __hwasan_test_shadow(reinterpret_cast<void *>(tagged_addr), access_size);
+  CHECK(offset >= 0 && offset < static_cast<sptr>(access_size));
+  tag_t ptr_tag = GetTagFromPointer(tagged_addr);
+  tag_t *tag_ptr =
+      reinterpret_cast<tag_t *>(MemToShadow(untagged_addr + offset));
+  tag_t mem_tag = *tag_ptr;
+
+  Printf("%s", d.Access());
+  Printf("%s of size %zu at %p tags: %02x/%02x (ptr/mem) in thread T%zd\n",
+         is_store ? "WRITE" : "READ", access_size, untagged_addr, ptr_tag,
+         mem_tag, t->unique_id());
+  if (offset != 0)
+    Printf("Invalid access starting at offset [%zu, %zu)\n", offset,
+           Min(access_size, static_cast<uptr>(offset) + (1 << kShadowScale)));
+  Printf("%s", d.Default());
+
+  stack->Print();
+
+  PrintAddressDescription(tagged_addr, access_size,
+                          current_stack_allocations.get());
+  t->Announce();
+
+  PrintTagsAroundAddr(tag_ptr);
+
+  if (registers_frame)
+    ReportRegisters(registers_frame, pc);
+
+  ReportErrorSummary(bug_type, stack);
+}
+
+// See the frame breakdown defined in __hwasan_tag_mismatch (from
+// hwasan_tag_mismatch_aarch64.S).
+void ReportRegisters(uptr *frame, uptr pc) {
+  Printf("Registers where the failure occurred (pc %p):\n", pc);
+
+  // We explicitly print a single line (4 registers/line) each iteration to
+  // reduce the amount of logcat error messages printed. Each Printf() will
+  // result in a new logcat line, irrespective of whether a newline is present,
+  // and so we wish to reduce the number of Printf() calls we have to make.
+  Printf("    x0  %016llx  x1  %016llx  x2  %016llx  x3  %016llx\n",
+       frame[0], frame[1], frame[2], frame[3]);
+  Printf("    x4  %016llx  x5  %016llx  x6  %016llx  x7  %016llx\n",
+       frame[4], frame[5], frame[6], frame[7]);
+  Printf("    x8  %016llx  x9  %016llx  x10 %016llx  x11 %016llx\n",
+       frame[8], frame[9], frame[10], frame[11]);
+  Printf("    x12 %016llx  x13 %016llx  x14 %016llx  x15 %016llx\n",
+       frame[12], frame[13], frame[14], frame[15]);
+  Printf("    x16 %016llx  x17 %016llx  x18 %016llx  x19 %016llx\n",
+       frame[16], frame[17], frame[18], frame[19]);
+  Printf("    x20 %016llx  x21 %016llx  x22 %016llx  x23 %016llx\n",
+       frame[20], frame[21], frame[22], frame[23]);
+  Printf("    x24 %016llx  x25 %016llx  x26 %016llx  x27 %016llx\n",
+       frame[24], frame[25], frame[26], frame[27]);
+  Printf("    x28 %016llx  x29 %016llx  x30 %016llx\n",
+       frame[28], frame[29], frame[30]);
+}
+
+}  // namespace __hwasan