[hwasan] do not check if freed pointer belonged to allocator.

[fmayer]

Summary

In that case it is very likely that there will be a tag mismatch anyway.

We handle the case that the pointer belongs to neither of the allocators
by getting a nullptr from allocator.GetBlockBegin.

[eugenis]

LGTM

[thakis]

This seems to break tests: http://45.33.8.238/linux/54105/step_10.txt

Any idea what's going wrong there?

(@pcc too)

[fmayer]

Reverted by rGde916a7b12adc842a2cc23505d78412e8b5166d2.

[fmayer]

non-app memory is always invalid free.

[fmayer]

fix MemIsApp

[fmayer]

Please take another look. Fixed the test failure.

[fmayer]

clang format

[eugenis]

LGTM

compiler-rt/lib/hwasan/hwasan_allocator.cpp

static bool PointerAndMemoryTagsMatch(void *tagged_ptr) {
   tag_t mem_tag = *reinterpret_cast<tag_t *>(
       MemToShadow(reinterpret_cast<uptr>(UntagPtr(tagged_ptr))));
   return PossiblyShortTagMatches(mem_tag, tagged_uptr, 1);
 }
 
 static bool CheckInvalidFree(StackTrace *stack, void *untagged_ptr,
                              void *tagged_ptr) {
   // This function can return true if halt_on_error is false.
-  if (!allocator.PointerIsMine(untagged_ptr) ||
-      !PointerAndMemoryTagsMatch(tagged_ptr)) {
+  if (!PointerAndMemoryTagsMatch(tagged_ptr)) {
     ReportInvalidFree(stack, reinterpret_cast<uptr>(tagged_ptr));
     return true;
   }
   return false;
 }
 
 static void HwasanDeallocate(StackTrace *stack, void *tagged_ptr) {
   CHECK(tagged_ptr);