From 1e406814dd21aad7da6bd1c1a8e0c6f1c1cd5369 Mon Sep 17 00:00:00 2001 From: Thurston Dang Date: Sat, 30 Aug 2025 00:03:56 -0700 Subject: [PATCH] =?UTF-8?q?Revert=20"[msan]=20Detect=20dereferencing=20zer?= =?UTF-8?q?o-alloc=20as=20use-of-uninitialized-value=20=E2=80=A6"?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This reverts commit 8784dcef3485a3862e5cacc9e18c646d0225483b. --- compiler-rt/lib/msan/msan_allocator.cpp | 6 ------ compiler-rt/test/msan/zero_alloc.cpp | 4 ++++ 2 files changed, 4 insertions(+), 6 deletions(-) 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 #include