[compiler-rt] f7c2833 - [HWASan] Leave pointer tagged when calling memmove.

[Matt Morehouse via llvm-commits]

Author: Matt Morehouse
Date: 2022-01-28T06:15:38-08:00
New Revision: f7c28332de71e55f1ab1b0fef72d598e427db3c3

URL: https://github.com/llvm/llvm-project/commit/f7c28332de71e55f1ab1b0fef72d598e427db3c3
DIFF: https://github.com/llvm/llvm-project/commit/f7c28332de71e55f1ab1b0fef72d598e427db3c3.diff

LOG: [HWASan] Leave pointer tagged when calling memmove.

Fixes a false positive that occurs when a user-implemented memmove is
instrumented by HWASan.

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D118180

Added: 
    compiler-rt/test/hwasan/TestCases/custom-memmove.c

Modified: 
    compiler-rt/lib/hwasan/hwasan_memintrinsics.cpp

Removed: 
    


################################################################################
diff  --git a/compiler-rt/lib/hwasan/hwasan_memintrinsics.cpp b/compiler-rt/lib/hwasan/hwasan_memintrinsics.cpp
index fab017aae60be..ea7f5ce40b074 100644
--- a/compiler-rt/lib/hwasan/hwasan_memintrinsics.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_memintrinsics.cpp
@@ -40,5 +40,5 @@ void *__hwasan_memmove(void *to, const void *from, uptr size) {
       reinterpret_cast<uptr>(to), size);
   CheckAddressSized<ErrorAction::Recover, AccessType::Load>(
       reinterpret_cast<uptr>(from), size);
-  return memmove(UntagPtr(to), UntagPtr(from), size);
+  return memmove(to, from, size);
 }

diff  --git a/compiler-rt/test/hwasan/TestCases/custom-memmove.c b/compiler-rt/test/hwasan/TestCases/custom-memmove.c
new file mode 100644
index 0000000000000..7b15e06234deb
--- /dev/null
+++ b/compiler-rt/test/hwasan/TestCases/custom-memmove.c
@@ -0,0 +1,39 @@
+// Test that custom memmove implementations instrumented by HWASan do not cause
+// false positives.
+
+// RUN: %clang_hwasan %s -o %t
+// RUN: %run %t
+
+#include <assert.h>
+#include <sanitizer/hwasan_interface.h>
+#include <stdlib.h>
+
+void *memmove(void *Dest, const void *Src, size_t N) {
+  char *Tmp = (char *)malloc(N);
+  char *D = (char *)Dest;
+  const char *S = (const char *)Src;
+
+  for (size_t I = 0; I < N; ++I)
+    Tmp[I] = S[I];
+  for (size_t I = 0; I < N; ++I)
+    D[I] = Tmp[I];
+
+  free(Tmp);
+  return Dest;
+}
+
+int main() {
+  __hwasan_enable_allocator_tagging();
+
+  const size_t BufSize = 64;
+  char *Buf = (char *)malloc(BufSize);
+
+  for (size_t I = 0; I < BufSize; ++I)
+    Buf[I] = I;
+  memmove(Buf + BufSize / 2, Buf, BufSize / 2);
+  for (size_t I = 0; I < BufSize; ++I)
+    assert(Buf[I] == I % (BufSize / 2));
+
+  free(Buf);
+  return 0;
+}