[sanitizer] Decorate /proc/self/maps on Android.

[eugenis]

Summary

Refactor the way /proc/self/maps entries are annotated to support most
(all?) posix platforms, with a special implementation for Android.
Extend the set of decorated Mmap* calls.

Generic implementation has limits (max number of files under /dev/shm is
64K on my machine), which can be conceivably reached when sanitizing
multiple programs at once. Android implemenation is essentially free, and
enabled by default.

The test in sanitizer_common is copied to hwasan and not reused directly
because hwasan fails way too many common tests at the moment.

[eugenis]

.

[eugenis]

.

[eugenis]

compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cc

353 ↗

(On Diff #185210)

@flowerhack FYI this is resolved by internal_open-ing /dev/shm instead of relying on shm_open.

[pcc]

The GetNamedMappingFd and DecorateMapping APIs seem a little awkwards to me. Everyone is using them as GetNamedMappingFd/mmap/DecorateMapping except for one place in hwasan. Would it make more sense to have a single function that does GetNamedMappingFd/mmap/DecorateMapping and continue using PR_SET_VMA_ANON_NAME in hwasan?

[eugenis]

.

[eugenis]

In D57720#1386140, @pcc wrote:

The GetNamedMappingFd and DecorateMapping APIs seem a little awkwards to me. Everyone is using them as GetNamedMappingFd/mmap/DecorateMapping except for one place in hwasan. Would it make more sense to have a single function that does GetNamedMappingFd/mmap/DecorateMapping and continue using PR_SET_VMA_ANON_NAME in hwasan?

Yes, this is way better.

[pcc]

LGTM

[eugenis]

Btw, I've pushed the RSS utility here:
https://github.com/google/sanitizers/blob/master/hwaddress-sanitizer/scan.cc
It depends on this change to find the shadow region. It is hwasan-specific, but can be easily adapted to other sanitizers if needed.
It's also really ugly, but I don't want to invest time in beautifying it.

compiler-rt/trunk/lib/cfi/cfi.cc

#if SANITIZER_LINUX
     void *res = mremap((void *)shadow_, GetShadowSize(), GetShadowSize(),
                        MREMAP_MAYMOVE | MREMAP_FIXED, (void *)main_shadow);
     CHECK(res != MAP_FAILED);
 #elif SANITIZER_NETBSD
     void *res = mremap((void *)shadow_, GetShadowSize(), (void *)main_shadow,
                        GetShadowSize(), MAP_FIXED);
     CHECK(res != MAP_FAILED);
 #else
-    void *res = MmapFixedOrDie(shadow_, GetShadowSize());
+    void *res = MmapFixedOrDie(shadow_, GetShadowSize(), "cfi shadow");
     CHECK(res != MAP_FAILED);
     ::memcpy(&shadow_, &main_shadow, GetShadowSize());
 #endif
   } else {
     // Initial setup.
     CHECK_EQ(kCfiShadowLimitsStorageSize, GetPageSizeCached());
     CHECK_EQ(0, GetShadow());
     cfi_shadow_limits_storage.limits.start = shadow_;

compiler-rt/trunk/lib/hwasan/hwasan.cc

s.append(
       thread_stats.total_stack_size,
       thread_stats.n_live_threads * thread_list.MemoryUsedPerThread(),
       sds->allocated, sds->n_uniq_ids, asc[AllocatorStatMapped]);
 }
 
 #if SANITIZER_ANDROID
 static char *memory_usage_buffer = nullptr;
 
-#define PR_SET_VMA 0x53564d41
-#define PR_SET_VMA_ANON_NAME 0
-
 static void InitMemoryUsage() {
   memory_usage_buffer =
       (char *)MmapOrDie(kMemoryUsageBufferSize, "memory usage string");
   CHECK(memory_usage_buffer);
   memory_usage_buffer[0] = '\0';
-  CHECK(internal_prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME,
-                       (uptr)memory_usage_buffer, kMemoryUsageBufferSize,
-                       (uptr)memory_usage_buffer) == 0);
+  DecorateMapping((uptr)memory_usage_buffer, kMemoryUsageBufferSize,
+                  memory_usage_buffer);
 }
 
 void UpdateMemoryUsage() {
   if (!flags()->export_memory_stats)
     return;
   if (!memory_usage_buffer)
     InitMemoryUsage();
   InternalScopedString s(kMemoryUsageBufferSize);

compiler-rt/trunk/lib/sanitizer_common/sanitizer_allocator_primary64.h

if (kUsingConstantSpaceBeg) {
       CHECK_EQ(kSpaceBeg, address_range.Init(TotalSpaceSize,
                                              PrimaryAllocatorName, kSpaceBeg));
     } else {
       NonConstSpaceBeg = address_range.Init(TotalSpaceSize,
                                             PrimaryAllocatorName);
       CHECK_NE(NonConstSpaceBeg, ~(uptr)0);
     }
     SetReleaseToOSIntervalMs(release_to_os_interval_ms);
-    MapWithCallbackOrDie(SpaceEnd(), AdditionalSize());
+    MapWithCallbackOrDie(SpaceEnd(), AdditionalSize(),
+                         "SizeClassAllocator: region info");
     // Check that the RegionInfo array is aligned on the CacheLine size.
     DCHECK_EQ(SpaceEnd() % kCacheLineSize, 0);
   }
 
   s32 ReleaseToOSIntervalMs() const {
     return atomic_load(&release_to_os_interval_ms_, memory_order_relaxed);
   }
 
if (offset >> (SANITIZER_WORDSIZE / 2))
       return offset / size;
     return (u32)offset / (u32)size;
   }
 
   CompactPtrT *GetFreeArray(uptr region_beg) const {
     return reinterpret_cast<CompactPtrT *>(GetMetadataEnd(region_beg));
   }
 
-  bool MapWithCallback(uptr beg, uptr size) {
-    uptr mapped = address_range.Map(beg, size);
+  bool MapWithCallback(uptr beg, uptr size, const char *name) {
+    uptr mapped = address_range.Map(beg, size, name);
     if (UNLIKELY(!mapped))
       return false;
     CHECK_EQ(beg, mapped);
     MapUnmapCallback().OnMap(beg, size);
     return true;
   }
 
-  void MapWithCallbackOrDie(uptr beg, uptr size) {
-    CHECK_EQ(beg, address_range.MapOrDie(beg, size));
+  void MapWithCallbackOrDie(uptr beg, uptr size, const char *name) {
+    CHECK_EQ(beg, address_range.MapOrDie(beg, size, name));
     MapUnmapCallback().OnMap(beg, size);
   }
 
   void UnmapWithCallbackOrDie(uptr beg, uptr size) {
     MapUnmapCallback().OnUnmap(beg, size);
     address_range.Unmap(beg, size);
   }
 
   bool EnsureFreeArraySpace(RegionInfo *region, uptr region_beg,
                             uptr num_freed_chunks) {
     uptr needed_space = num_freed_chunks * sizeof(CompactPtrT);
     if (region->mapped_free_array < needed_space) {
       uptr new_mapped_free_array = RoundUpTo(needed_space, kFreeArrayMapSize);
       CHECK_LE(new_mapped_free_array, kFreeArraySize);
       uptr current_map_end = reinterpret_cast<uptr>(GetFreeArray(region_beg)) +
                              region->mapped_free_array;
       uptr new_map_size = new_mapped_free_array - region->mapped_free_array;
-      if (UNLIKELY(!MapWithCallback(current_map_end, new_map_size)))
+      if (UNLIKELY(!MapWithCallback(current_map_end, new_map_size,
+                                    "SizeClassAllocator: freearray")))
         return false;
       region->mapped_free_array = new_mapped_free_array;
     }
     return true;
   }
 
   // Check whether this size class is exhausted.
   bool IsRegionExhausted(RegionInfo *region, uptr class_id,
if (LIKELY(total_user_bytes > region->mapped_user)) {
           region->rtoi.last_release_at_ns = MonotonicNanoTime();
       }
       // Do the mmap for the user memory.
       const uptr user_map_size =
           RoundUpTo(total_user_bytes - region->mapped_user, kUserMapSize);
       if (UNLIKELY(IsRegionExhausted(region, class_id, user_map_size)))
         return false;
       if (UNLIKELY(!MapWithCallback(region_beg + region->mapped_user,
-                                    user_map_size)))
+                                    user_map_size,
+                                    "SizeClassAllocator: region data")))
         return false;
       stat->Add(AllocatorStatMapped, user_map_size);
       region->mapped_user += user_map_size;
     }
     const uptr new_chunks_count =
         (region->mapped_user - region->allocated_user) / size;
 
     if (kMetadataSize) {
       // Calculate the required space for metadata.
       const uptr total_meta_bytes =
           region->allocated_meta + new_chunks_count * kMetadataSize;
       const uptr meta_map_size = (total_meta_bytes > region->mapped_meta) ?
           RoundUpTo(total_meta_bytes - region->mapped_meta, kMetaMapSize) : 0;
       // Map more space for metadata, if necessary.
       if (meta_map_size) {
         if (UNLIKELY(IsRegionExhausted(region, class_id, meta_map_size)))
           return false;
         if (UNLIKELY(!MapWithCallback(
             GetMetadataEnd(region_beg) - region->mapped_meta - meta_map_size,
-            meta_map_size)))
+            meta_map_size, "SizeClassAllocator: region metadata")))
           return false;
         region->mapped_meta += meta_map_size;
       }
     }
 
     // If necessary, allocate more space for the free array and populate it with
     // newly allocated chunks.
     const uptr total_freed_chunks = region->num_freed_chunks + new_chunks_count;

compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.h

 }
 void UnmapOrDie(void *addr, uptr size);
 // Behaves just like MmapOrDie, but tolerates out of memory condition, in that
 // case returns nullptr.
 void *MmapOrDieOnFatalError(uptr size, const char *mem_type);
 bool MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name = nullptr)
      WARN_UNUSED_RESULT;
 void *MmapNoReserveOrDie(uptr size, const char *mem_type);
-void *MmapFixedOrDie(uptr fixed_addr, uptr size);
+void *MmapFixedOrDie(uptr fixed_addr, uptr size, const char *name = nullptr);
 // Behaves just like MmapFixedOrDie, but tolerates out of memory condition, in
 // that case returns nullptr.
-void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size);
+void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size,
+                                 const char *name = nullptr);
 void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name = nullptr);
 void *MmapNoAccess(uptr size);
 // Map aligned chunk of address space; size and alignment are powers of two.
 // Dies on all but out of memory errors, in the latter case returns nullptr.
 void *MmapAlignedOrDieOnFatalError(uptr size, uptr alignment,
                                    const char *mem_type);
 // Disallow access to a memory range.  Use MmapFixedNoAccess to allocate an
 // unaccessible memory.

 // Check if the built VMA size matches the runtime one.
 void CheckVMASize();
 void RunMallocHooks(const void *ptr, uptr size);
 void RunFreeHooks(const void *ptr);
 
 class ReservedAddressRange {
  public:
   uptr Init(uptr size, const char *name = nullptr, uptr fixed_addr = 0);
-  uptr Map(uptr fixed_addr, uptr size);
-  uptr MapOrDie(uptr fixed_addr, uptr size);
+  uptr Map(uptr fixed_addr, uptr size, const char *name = nullptr);
+  uptr MapOrDie(uptr fixed_addr, uptr size, const char *name = nullptr);
   void Unmap(uptr addr, uptr size);
   void *base() const { return base_; }
   uptr size() const { return size_; }
 
  private:
   void* base_;
   uptr size_;
   const char* name_;

compiler-rt/trunk/lib/sanitizer_common/sanitizer_flags.inc

COMMON_FLAG(bool, intercept_intrin, true,
             "If set, uses custom wrappers for memset/memcpy/memmove "
             "intrinsics to find more errors.")
 COMMON_FLAG(bool, intercept_stat, true,
             "If set, uses custom wrappers for *stat functions "
             "to find more errors.")
 COMMON_FLAG(bool, intercept_send, true,
             "If set, uses custom wrappers for send* functions "
             "to find more errors.")
-COMMON_FLAG(bool, decorate_proc_maps, false, "If set, decorate sanitizer "
-                                             "mappings in /proc/self/maps with "
-                                             "user-readable names")
+COMMON_FLAG(bool, decorate_proc_maps, (bool)SANITIZER_ANDROID,
+            "If set, decorate sanitizer mappings in /proc/self/maps with "
 COMMON_FLAG(int, exitcode, 1, "Override the program exit status if the tool "
                               "found an error")
 COMMON_FLAG(
     bool, abort_on_error, (bool)SANITIZER_ANDROID || (bool)SANITIZER_MAC,
     "If set, the tool calls abort() instead of _exit() after printing the "
     "error report.")
 COMMON_FLAG(bool, suppress_equal_pcs, true,
             "Deduplicate multiple reports for single source location in "

compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.h

 
 bool IsStateDetached(int state);
 
 // Move the fd out of {0, 1, 2} range.
 fd_t ReserveStandardFds(fd_t fd);
 
 bool ShouldMockFailureToOpen(const char *path);
 
+// Create a non-file mapping with a given /proc/self/maps name.
+uptr MmapNamed(void *addr, uptr length, int prot, int flags, const char *name);
+
+// Platforms should implement at most one of these.
+// 1. Provide a pre-decorated file descriptor to use instead of an anonymous
+// mapping.
+int GetNamedMappingFd(const char *name, uptr size, int *flags);
+// 2. Add name to an existing anonymous mapping. The caller must keep *name
+// alive at least as long as the mapping exists.
+void DecorateMapping(uptr addr, uptr size, const char *name);
+
+
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_POSIX_H

compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix.cc

 
 // ------------- sanitizer_common.h
 uptr GetMmapGranularity() {
   return GetPageSize();
 }
 
 void *MmapOrDie(uptr size, const char *mem_type, bool raw_report) {
   size = RoundUpTo(size, GetPageSizeCached());
-  uptr res = internal_mmap(nullptr, size,
-                           PROT_READ | PROT_WRITE,
-                           MAP_PRIVATE | MAP_ANON, -1, 0);
+  uptr res = MmapNamed(nullptr, size, PROT_READ | PROT_WRITE,
+                       MAP_PRIVATE | MAP_ANON, mem_type);
   int reserrno;
   if (UNLIKELY(internal_iserror(res, &reserrno)))
     ReportMmapFailureAndDie(size, mem_type, "allocate", reserrno, raw_report);
   IncreaseTotalMmap(size);
   return (void *)res;
 }
 
 void UnmapOrDie(void *addr, uptr size) {
   if (!addr || !size) return;
   uptr res = internal_munmap(addr, size);
   if (UNLIKELY(internal_iserror(res))) {
     Report("ERROR: %s failed to deallocate 0x%zx (%zd) bytes at address %p\n",
            SanitizerToolName, size, size, addr);
     CHECK("unable to unmap" && 0);
   }
   DecreaseTotalMmap(size);
 }
 
 void *MmapOrDieOnFatalError(uptr size, const char *mem_type) {
   size = RoundUpTo(size, GetPageSizeCached());
-  uptr res = internal_mmap(nullptr, size,
-                           PROT_READ | PROT_WRITE,
-                           MAP_PRIVATE | MAP_ANON, -1, 0);
+  uptr res = MmapNamed(nullptr, size, PROT_READ | PROT_WRITE,
+                       MAP_PRIVATE | MAP_ANON, mem_type);
   int reserrno;
   if (UNLIKELY(internal_iserror(res, &reserrno))) {
     if (reserrno == ENOMEM)
       return nullptr;
     ReportMmapFailureAndDie(size, mem_type, "allocate", reserrno);
   }
   IncreaseTotalMmap(size);
   return (void *)res;
void *MmapAlignedOrDieOnFatalError(uptr size, uptr alignment,
   }
   uptr end = res + size;
   if (end != map_end)
     UnmapOrDie((void*)end, map_end - end);
   return (void*)res;
 }
 
 void *MmapNoReserveOrDie(uptr size, const char *mem_type) {
-  uptr PageSize = GetPageSizeCached();
-  uptr p = internal_mmap(nullptr,
-                         RoundUpTo(size, PageSize),
-                         PROT_READ | PROT_WRITE,
-                         MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
-                         -1, 0);
+  size = RoundUpTo(size, GetPageSizeCached());
+  uptr p = MmapNamed(nullptr, size, PROT_READ | PROT_WRITE,
+                     MAP_PRIVATE | MAP_ANON | MAP_NORESERVE, mem_type);
   int reserrno;
   if (UNLIKELY(internal_iserror(p, &reserrno)))
     ReportMmapFailureAndDie(size, mem_type, "allocate noreserve", reserrno);
   IncreaseTotalMmap(size);
   return (void *)p;
 }
 
-void *MmapFixedImpl(uptr fixed_addr, uptr size, bool tolerate_enomem) {
-  uptr PageSize = GetPageSizeCached();
-  uptr p = internal_mmap((void*)(fixed_addr & ~(PageSize - 1)),
-      RoundUpTo(size, PageSize),
-      PROT_READ | PROT_WRITE,
-      MAP_PRIVATE | MAP_ANON | MAP_FIXED,
-      -1, 0);
+static void *MmapFixedImpl(uptr fixed_addr, uptr size, bool tolerate_enomem,
+                           const char *name) {
+  size = RoundUpTo(size, GetPageSizeCached());
+  fixed_addr = RoundDownTo(fixed_addr, GetPageSizeCached());
+  uptr p = MmapNamed((void *)fixed_addr, size, PROT_READ | PROT_WRITE,
+                     MAP_PRIVATE | MAP_ANON | MAP_FIXED, name);
   int reserrno;
   if (UNLIKELY(internal_iserror(p, &reserrno))) {
     if (tolerate_enomem && reserrno == ENOMEM)
       return nullptr;
     char mem_type[40];
     internal_snprintf(mem_type, sizeof(mem_type), "memory at address 0x%zx",
                       fixed_addr);
     ReportMmapFailureAndDie(size, mem_type, "allocate", reserrno);
   }
   IncreaseTotalMmap(size);
   return (void *)p;
 }
 
-void *MmapFixedOrDie(uptr fixed_addr, uptr size) {
-  return MmapFixedImpl(fixed_addr, size, false /*tolerate_enomem*/);
+void *MmapFixedOrDie(uptr fixed_addr, uptr size, const char *name) {
+  return MmapFixedImpl(fixed_addr, size, false /*tolerate_enomem*/, name);
 }
 
-void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size) {
-  return MmapFixedImpl(fixed_addr, size, true /*tolerate_enomem*/);
+void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size, const char *name) {
+  return MmapFixedImpl(fixed_addr, size, true /*tolerate_enomem*/, name);
 }
 
 bool MprotectNoAccess(uptr addr, uptr size) {
   return 0 == internal_mprotect((void*)addr, size, PROT_NONE);
 }
 
 bool MprotectReadOnly(uptr addr, uptr size) {
   return 0 == internal_mprotect((void *)addr, size, PROT_READ);
fd_t ReserveStandardFds(fd_t fd) {
   return fd;
 }
 
 bool ShouldMockFailureToOpen(const char *path) {
   return common_flags()->test_only_emulate_no_memorymap &&
          internal_strncmp(path, "/proc/", 6) == 0;
 }
 
+#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_GO
+int GetNamedMappingFd(const char *name, uptr size, int *flags) {
+  if (!common_flags()->decorate_proc_maps || !name)
+    return -1;
+  char shmname[200];
+  CHECK(internal_strlen(name) < sizeof(shmname) - 10);
+  internal_snprintf(shmname, sizeof(shmname), "/dev/shm/%zu [%s]",
+                    internal_getpid(), name);
+  int fd = ReserveStandardFds(
+      internal_open(shmname, O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, S_IRWXU));
+  CHECK_GE(fd, 0);
+  int res = internal_ftruncate(fd, size);
+  CHECK_EQ(0, res);
+  res = internal_unlink(shmname);
+  CHECK_EQ(0, res);
+  *flags &= ~(MAP_ANON | MAP_ANONYMOUS);
+  return fd;
+}
+#else
+int GetNamedMappingFd(const char *name, uptr size, int *flags) {
+  return -1;
+}
+#endif
+
+#if SANITIZER_ANDROID
+#define PR_SET_VMA 0x53564d41
+#define PR_SET_VMA_ANON_NAME 0
+void DecorateMapping(uptr addr, uptr size, const char *name) {
+  if (!common_flags()->decorate_proc_maps || !name)
+    return;
+  CHECK(internal_prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, addr, size,
+                       (uptr)name) == 0);
+}
+#else
+void DecorateMapping(uptr addr, uptr size, const char *name) {
+}
+#endif
+
+uptr MmapNamed(void *addr, uptr length, int prot, int flags, const char *name) {
+  int fd = GetNamedMappingFd(name, length, &flags);
+  uptr res = internal_mmap(addr, length, prot, flags, fd, 0);
+  if (!internal_iserror(res))
+    DecorateMapping(res, length, name);
+  return res;
+}
+
+
 } // namespace __sanitizer
 
 #endif // SANITIZER_POSIX

compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix_libcdep.cc

 void PlatformPrepareForSandboxing(__sanitizer_sandbox_arguments *args) {
   // Some kinds of sandboxes may forbid filesystem access, so we won't be able
   // to read the file mappings from /proc/self/maps. Luckily, neither the
   // process will be able to load additional libraries, so it's fine to use the
   // cached mappings.
   MemoryMappingLayout::CacheMemoryMappings();
 }
 
-#if SANITIZER_ANDROID || SANITIZER_GO
-int GetNamedMappingFd(const char *name, uptr size) {
-  return -1;
-}
-#else
-int GetNamedMappingFd(const char *name, uptr size) {
-  if (!common_flags()->decorate_proc_maps)
-    return -1;
-  char shmname[200];
-  CHECK(internal_strlen(name) < sizeof(shmname) - 10);
-  internal_snprintf(shmname, sizeof(shmname), "%zu [%s]", internal_getpid(),
-                    name);
-  int fd = shm_open(shmname, O_RDWR | O_CREAT | O_TRUNC, S_IRWXU);
-  CHECK_GE(fd, 0);
-  int res = internal_ftruncate(fd, size);
-  CHECK_EQ(0, res);
-  res = shm_unlink(shmname);
-  CHECK_EQ(0, res);
-  return fd;
-}
-#endif
-
 bool MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
-  int fd = name ? GetNamedMappingFd(name, size) : -1;
-  unsigned flags = MAP_PRIVATE | MAP_FIXED | MAP_NORESERVE;
-  if (fd == -1) flags |= MAP_ANON;
-
-  uptr PageSize = GetPageSizeCached();
-  uptr p = internal_mmap((void *)(fixed_addr & ~(PageSize - 1)),
-                         RoundUpTo(size, PageSize), PROT_READ | PROT_WRITE,
-                         flags, fd, 0);
+  size = RoundUpTo(size, GetPageSizeCached());
+  fixed_addr = RoundDownTo(fixed_addr, GetPageSizeCached());
+  uptr p = MmapNamed((void *)fixed_addr, size, PROT_READ | PROT_WRITE,
+                     MAP_PRIVATE | MAP_FIXED | MAP_NORESERVE | MAP_ANON, name);
   int reserrno;
   if (internal_iserror(p, &reserrno)) {
     Report("ERROR: %s failed to "
            "allocate 0x%zx (%zd) bytes at address %zx (errno: %d)\n",
            SanitizerToolName, size, size, fixed_addr, reserrno);
     return false;
   }
   IncreaseTotalMmap(size);
   return true;
 }
 
 uptr ReservedAddressRange::Init(uptr size, const char *name, uptr fixed_addr) {
-  // We don't pass `name` along because, when you enable `decorate_proc_maps`
-  // AND actually use a named mapping AND are using a sanitizer intercepting
-  // `open` (e.g. TSAN, ESAN), then you'll get a failure during initialization.
-  // TODO(flowerhack): Fix the implementation of GetNamedMappingFd to solve
-  // this problem.
-  base_ = fixed_addr ? MmapFixedNoAccess(fixed_addr, size) : MmapNoAccess(size);
+  base_ = fixed_addr ? MmapFixedNoAccess(fixed_addr, size, name)
+                     : MmapNoAccess(size);
   size_ = size;
   name_ = name;
   (void)os_handle_;  // unsupported
   return reinterpret_cast<uptr>(base_);
 }
 
 // Uses fixed_addr for now.
 // Will use offset instead once we've implemented this function for real.
-uptr ReservedAddressRange::Map(uptr fixed_addr, uptr size) {
-  return reinterpret_cast<uptr>(MmapFixedOrDieOnFatalError(fixed_addr, size));
+uptr ReservedAddressRange::Map(uptr fixed_addr, uptr size, const char *name) {
+  return reinterpret_cast<uptr>(
+      MmapFixedOrDieOnFatalError(fixed_addr, size, name));
 }
 
-uptr ReservedAddressRange::MapOrDie(uptr fixed_addr, uptr size) {
-  return reinterpret_cast<uptr>(MmapFixedOrDie(fixed_addr, size));
+uptr ReservedAddressRange::MapOrDie(uptr fixed_addr, uptr size,
+                                    const char *name) {
+  return reinterpret_cast<uptr>(MmapFixedOrDie(fixed_addr, size, name));
 }
 
 void ReservedAddressRange::Unmap(uptr addr, uptr size) {
   CHECK_LE(size, size_);
   if (addr == reinterpret_cast<uptr>(base_))
     // If we unmap the whole range, just null out the base.
     base_ = (size == size_) ? nullptr : reinterpret_cast<void*>(addr + size);
   else
     CHECK_EQ(addr + size, reinterpret_cast<uptr>(base_) + size_);
   size_ -= size;
   UnmapOrDie(reinterpret_cast<void*>(addr), size);
 }
 
 void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name) {
-  int fd = name ? GetNamedMappingFd(name, size) : -1;
-  unsigned flags = MAP_PRIVATE | MAP_FIXED | MAP_NORESERVE;
-  if (fd == -1) flags |= MAP_ANON;
-
-  return (void *)internal_mmap((void *)fixed_addr, size, PROT_NONE, flags, fd,
-                               0);
+  return (void *)MmapNamed((void *)fixed_addr, size, PROT_NONE,
+                           MAP_PRIVATE | MAP_FIXED | MAP_NORESERVE | MAP_ANON,
+                           name);
 }
 
 void *MmapNoAccess(uptr size) {
   unsigned flags = MAP_PRIVATE | MAP_ANON | MAP_NORESERVE;
   return (void *)internal_mmap(nullptr, size, PROT_NONE, flags, -1, 0);
 }
 
 // This function is defined elsewhere if we intercepted pthread_attr_getstack.

compiler-rt/trunk/lib/sanitizer_common/sanitizer_win.cc

Report("ERROR: %s failed to "
            SanitizerToolName, size, size, fixed_addr, GetLastError());
     return false;
   }
   return true;
 }
 
 // Memory space mapped by 'MmapFixedOrDie' must have been reserved by
 // 'MmapFixedNoAccess'.
-void *MmapFixedOrDie(uptr fixed_addr, uptr size) {
+void *MmapFixedOrDie(uptr fixed_addr, uptr size, const char *name) {
   void *p = VirtualAlloc((LPVOID)fixed_addr, size,
       MEM_COMMIT, PAGE_READWRITE);
   if (p == 0) {
     char mem_type[30];
     internal_snprintf(mem_type, sizeof(mem_type), "memory at address 0x%zx",
                       fixed_addr);
     ReportMmapFailureAndDie(size, mem_type, "allocate", GetLastError());
   }
void ReservedAddressRange::Unmap(uptr addr, uptr size) {
   // Only unmap if it covers the entire range.
   CHECK((addr == reinterpret_cast<uptr>(base_)) && (size == size_));
   // We unmap the whole range, just null out the base.
   base_ = nullptr;
   size_ = 0;
   UnmapOrDie(reinterpret_cast<void*>(addr), size);
 }
 
-void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size) {
+void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size, const char *name) {
   void *p = VirtualAlloc((LPVOID)fixed_addr, size,
       MEM_COMMIT, PAGE_READWRITE);
   if (p == 0) {
     char mem_type[30];
     internal_snprintf(mem_type, sizeof(mem_type), "memory at address 0x%zx",
                       fixed_addr);
     return ReturnNullptrOnOOMOrDie(size, mem_type, "allocate");
   }

compiler-rt/trunk/test/hwasan/TestCases/Linux/decorate-proc-maps.c

+// RUN: %clang_hwasan -g %s -o %t
+// RUN: %env_hwasan_opts=decorate_proc_maps=1 %run %t 2>&1 | FileCheck %s --check-prefix=A
+// RUN: %env_hwasan_opts=decorate_proc_maps=1 %run %t 2>&1 | FileCheck %s --check-prefix=B
+
+// A:      rw-p {{.*}}hwasan threads]
+// A-NEXT: ---p {{.*}}shadow gap]
+// A-NEXT: rw-p {{.*}}low shadow]
+// A-NEXT: ---p {{.*}}shadow gap]
+// A-NEXT: rw-p {{.*}}high shadow]
+
+// B-DAG: rw-p {{.*}}SizeClassAllocator: region data]
+// B-DAG: rw-p {{.*}}SizeClassAllocator: region metadata]
+// B-DAG: rw-p {{.*}}SizeClassAllocator: freearray]
+// B-DAG: rw-p {{.*}}SizeClassAllocator: region info]
+// B-DAG: rw-p {{.*}}LargeMmapAllocator]
+// B-DAG: rw-p {{.*}}stack depot]
+
+#include <errno.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <stdlib.h>
+
+void CopyFdToFd(int in_fd, int out_fd) {
+  const size_t kBufSize = 0x10000;
+  static char buf[kBufSize];
+  while (1) {
+    ssize_t got = read(in_fd, buf, kBufSize);
+    if (got > 0) {
+      write(out_fd, buf, got);
+    } else if (got == 0) {
+      break;
+    } else if (errno != EAGAIN || errno != EWOULDBLOCK || errno != EINTR) {
+      fprintf(stderr, "error reading file, errno %d\n", errno);
+      abort();
+    }
+  }
+}
+
+void *ThreadFn(void *arg) {
+  (void)arg;
+  int fd = open("/proc/self/maps", O_RDONLY);
+  CopyFdToFd(fd, 2);
+  close(fd);
+  return NULL;
+}
+
+int main(void) {
+  pthread_t t;
+  void * volatile res = malloc(100);
+  void * volatile res2 = malloc(100000);
+  pthread_create(&t, 0, ThreadFn, 0);
+  pthread_join(t, 0);
+  return (int)(size_t)res;
+}