5 files changed, 45 insertions, 8 deletions
diff --git a/compiler-rt/lib/hwasan/hwasan_allocator.cc b/compiler-rt/lib/hwasan/hwasan_allocator.cc
index b9c379ea449..ddc0928625a 100644
--- a/compiler-rt/lib/hwasan/hwasan_allocator.cc
+++ b/compiler-rt/lib/hwasan/hwasan_allocator.cc
@@ -23,6 +23,14 @@
 
 namespace __hwasan {
 
+static Allocator allocator;
+static AllocatorCache fallback_allocator_cache;
+static SpinMutex fallback_mutex;
+static atomic_uint8_t hwasan_allocator_tagging_enabled;
+
+static const tag_t kFallbackAllocTag = 0xBB;
+static const tag_t kFallbackFreeTag = 0xBC;
+
 bool HwasanChunkView::IsAllocated() const {
   return metadata_ && metadata_->alloc_context_id && metadata_->requested_size;
 }
@@ -40,13 +48,13 @@ u32 HwasanChunkView::GetAllocStackId() const {
   return metadata_->alloc_context_id;
 }
 
-static Allocator allocator;
-static AllocatorCache fallback_allocator_cache;
-static SpinMutex fallback_mutex;
-static atomic_uint8_t hwasan_allocator_tagging_enabled;
+uptr HwasanChunkView::ActualSize() const {
+  return allocator.GetActuallyAllocatedSize(reinterpret_cast<void *>(block_));
+}
 
-static const tag_t kFallbackAllocTag = 0xBB;
-static const tag_t kFallbackFreeTag = 0xBC;
+bool HwasanChunkView::FromSmallHeap() const {
+  return allocator.FromPrimary(reinterpret_cast<void *>(block_));
+}
 
 void GetAllocatorStats(AllocatorStatCounters s) {
   allocator.GetStats(s);
diff --git a/compiler-rt/lib/hwasan/hwasan_allocator.h b/compiler-rt/lib/hwasan/hwasan_allocator.h
index 3589212d852..119ead886c0 100644
--- a/compiler-rt/lib/hwasan/hwasan_allocator.h
+++ b/compiler-rt/lib/hwasan/hwasan_allocator.h
@@ -76,7 +76,9 @@ class HwasanChunkView {
   uptr Beg() const;            // First byte of user memory
   uptr End() const;            // Last byte of user memory
   uptr UsedSize() const;       // Size requested by the user
+  uptr ActualSize() const;     // Size allocated by the allocator.
   u32 GetAllocStackId() const;
+  bool FromSmallHeap() const;
  private:
   uptr block_;
   Metadata *const metadata_;
diff --git a/compiler-rt/lib/hwasan/hwasan_report.cc b/compiler-rt/lib/hwasan/hwasan_report.cc
index 4c69b86c7c4..46373b9f145 100644
--- a/compiler-rt/lib/hwasan/hwasan_report.cc
+++ b/compiler-rt/lib/hwasan/hwasan_report.cc
@@ -95,6 +95,21 @@ void PrintAddressDescription(
   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,
diff --git a/compiler-rt/test/hwasan/TestCases/heap-buffer-overflow.c b/compiler-rt/test/hwasan/TestCases/heap-buffer-overflow.c
index 40b6e6e9d1d..6b0cf311d2e 100644
--- a/compiler-rt/test/hwasan/TestCases/heap-buffer-overflow.c
+++ b/compiler-rt/test/hwasan/TestCases/heap-buffer-overflow.c
@@ -17,10 +17,19 @@ int main(int argc, char **argv) {
   int size = argc < 3 ? 30 : atoi(argv[2]);
   char * volatile x = (char*)malloc(size);
   x[offset] = 42;
+// CHECK40: is a small unallocated heap chunk; size: 32 offset: 8
 // CHECK40: is located 10 bytes to the right of 30-byte region
+//
+// CHECK80: is a small unallocated heap chunk; size: 32 offset: 16
 // CHECK80: is located 50 bytes to the right of 30-byte region
+//
+// CHECKm30: is a small unallocated heap chunk; size: 32 offset: 2
 // CHECKm30: is located 30 bytes to the left of 30-byte region
+//
+// CHECKMm30: is a large allocated heap chunk; size: 1003520 offset: -30
 // CHECKMm30: is located 30 bytes to the left of 1000000-byte region
+//
+// CHECKM: is a large allocated heap chunk; size: 1003520 offset: 1000000
 // CHECKM: is located 0 bytes to the right of 1000000-byte region
   free(x);
 }
diff --git a/compiler-rt/test/hwasan/TestCases/use-after-free.c b/compiler-rt/test/hwasan/TestCases/use-after-free.c
index 3dae97b0caa..bc2c8d48f9d 100644
--- a/compiler-rt/test/hwasan/TestCases/use-after-free.c
+++ b/compiler-rt/test/hwasan/TestCases/use-after-free.c
@@ -23,13 +23,16 @@ int main() {
   // CHECK: [[TYPE]] of size 1 at {{.*}} tags: [[PTR_TAG:[0-9a-f][0-9a-f]]]/[[MEM_TAG:[0-9a-f][0-9a-f]]] (ptr/mem)
   // CHECK: #0 {{.*}} in main {{.*}}use-after-free.c:[[@LINE-2]]
 
+  // CHECK: is a small unallocated heap chunk; size: 16 offset: 5
+  // CHECK: is located 5 bytes inside of 10-byte region
+  //
   // CHECK: freed by thread {{.*}} here:
   // CHECK: #0 {{.*}} in {{.*}}free{{.*}} {{.*}}hwasan_interceptors.cc
-  // CHECK: #1 {{.*}} in main {{.*}}use-after-free.c:[[@LINE-11]]
+  // CHECK: #1 {{.*}} in main {{.*}}use-after-free.c:[[@LINE-14]]
 
   // CHECK: previously allocated here:
   // CHECK: #0 {{.*}} in {{.*}}malloc{{.*}} {{.*}}hwasan_interceptors.cc
-  // CHECK: #1 {{.*}} in main {{.*}}use-after-free.c:[[@LINE-16]]
+  // CHECK: #1 {{.*}} in main {{.*}}use-after-free.c:[[@LINE-19]]
   // CHECK: Memory tags around the buggy address (one tag corresponds to 16 bytes):
   // CHECK: =>{{.*}}[[MEM_TAG]]
   // CHECK: SUMMARY: HWAddressSanitizer: tag-mismatch {{.*}} in main