Revert "[msan] Detect dereferencing zero-alloc as use-of-uninitialized-value" #156148
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…d-value …" This reverts commit 8784dce.
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@llvm/pr-subscribers-compiler-rt-sanitizer Author: Thurston Dang (thurstond) ChangesReverts llvm/llvm-project#155944 Per post-commit discussion in #155944 (comment), this is detecting OOB access, which is not in scope for MSan. To be logically consistent with how MSan does not try to handle OOB in other cases, this patch reverts the MSan change. Dereferencing zero-alloc can be detected with ASan instead (as of #155943). Full diff: https://github.com/llvm/llvm-project/pull/156148.diff 2 Files Affected:
diff --git a/compiler-rt/lib/msan/msan_allocator.cpp b/compiler-rt/lib/msan/msan_allocator.cpp
index 64df863839c06..2b543db49d36e 100644
--- a/compiler-rt/lib/msan/msan_allocator.cpp
+++ b/compiler-rt/lib/msan/msan_allocator.cpp
@@ -230,12 +230,6 @@ static void *MsanAllocate(BufferedStackTrace *stack, uptr size, uptr alignment,
__msan_set_origin(allocated, size, o.raw_id());
}
}
-
- uptr actually_allocated_size = allocator.GetActuallyAllocatedSize(allocated);
- // For compatibility, the allocator converted 0-sized allocations into 1 byte
- if (size == 0 && actually_allocated_size > 0 && flags()->poison_in_malloc)
- __msan_poison(allocated, 1);
-
UnpoisonParam(2);
RunMallocHooks(allocated, size);
return allocated;
diff --git a/compiler-rt/test/msan/zero_alloc.cpp b/compiler-rt/test/msan/zero_alloc.cpp
index 6e38ce4c0a8f8..e60051872eba2 100644
--- a/compiler-rt/test/msan/zero_alloc.cpp
+++ b/compiler-rt/test/msan/zero_alloc.cpp
@@ -1,5 +1,9 @@
// RUN: %clang_msan -Wno-alloc-size -fsanitize-recover=memory %s -o %t && not %run %t 2>&1 | FileCheck %s
+// MSan doesn't catch this because internally it translates 0-byte allocations
+// into 1-byte
+// XFAIL: *
+
#include <malloc.h>
#include <stdio.h>
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I am asking to make more general. |
Reverts #155944
Per post-commit discussion in #155944 (comment), this is detecting OOB access, which is not in scope for MSan. To be logically consistent with how MSan does not try to handle OOB in other cases, this patch reverts the MSan change. Dereferencing zero-alloc can be detected with ASan instead (as of #155943).