diff --git a/compiler-rt/lib/scudo/standalone/combined.h b/compiler-rt/lib/scudo/standalone/combined.h --- a/compiler-rt/lib/scudo/standalone/combined.h +++ b/compiler-rt/lib/scudo/standalone/combined.h @@ -560,7 +560,16 @@ } } + // Try to detect deallocation with a wrong MTE tag by touching the first + // byte with a correctly tagged pointer. Skip zero-sized allocations that do + // not always store the correct tag value anywhere (for example, a zero + // size, 32 byte aligned allocation in a 32-byte size class will end up with + // header at offset 16 in the block, payload at offset 32, and no space to + // store the tag). const uptr Size = getSize(Ptr, &Header); + if (useMemoryTagging(Options) && Size != 0) + *reinterpret_cast(TaggedPtr); + if (DeleteSize && Options.get(OptionBit::DeleteSizeMismatch)) { if (UNLIKELY(DeleteSize != Size)) reportDeleteSizeMismatch(Ptr, DeleteSize, Size); diff --git a/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp b/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp --- a/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp +++ b/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp @@ -395,6 +395,27 @@ } } +SCUDO_TYPED_TEST(ScudoCombinedDeathTest, FreeWithTagMismatch) { + auto *Allocator = this->Allocator.get(); + + if (!Allocator->useMemoryTaggingTestOnly()) + return; + + // Check that double free is detected. + for (scudo::uptr SizeLog = 0U; SizeLog <= 20U; SizeLog++) { + const scudo::uptr Size = 1U << SizeLog; + EXPECT_DEATH( + { + disableDebuggerdMaybe(); + void *P = Allocator->allocate(Size, Origin); + scudo::uptr NewTag = (scudo::extractTag(reinterpret_cast(P)) + 1) % 16; + void *Q = scudo::addFixedTag(scudo::untagPointer(P), NewTag); + Allocator->deallocate(Q, Origin); + }, + ""); + } +} + SCUDO_TYPED_TEST(ScudoCombinedDeathTest, DisableMemoryTagging) { auto *Allocator = this->Allocator.get();