[hwasan] fix false positive when hwasan-match-all-tag flag is enabled and short granules are used

[Enna1]

Summary

When hwasan-match-all-tag flag is enabled and short granules are used, at the point checking if this is a short tag case, the tag from pointer is stored in X16 register,
which breaks the assumption that tag from shadow memory is stored in X16 register, this will cause a false positive.

[Enna1]

update

[Enna1]

update

[Enna1]

update

[vitalybuka]

compiler-rt/test/hwasan/TestCases/short-granule-and-match-all-tag.cpp

2–19

exit 0 is enough for this test

llvm/test/CodeGen/AArch64/hwasan-check-memaccess.ll

115 ↗

(On Diff #517136)

can you please precommit this test with the current state of HWASAN, so we can see a difference here

[Enna1]

• only test

[Enna1]

UNSUPPORTED: HWAddressSanitizer-x86_64 :: TestCases/short-granule-and-match-all-tag.cpp (19669 of 70430)

Pre-merge checks buildbot does not support HWASAN test, so we can not see this test failure in premerge checks .
Do you mean I create another differential only containing this testcase, commit it to llvm trunk and check if sanitizer-aarch64-linux-bootstrap-hwasan(https://lab.llvm.org/buildbot/#/builders/236) will fail?

[vitalybuka]

In D149252#4301314, @Enna1 wrote:

UNSUPPORTED: HWAddressSanitizer-x86_64 :: TestCases/short-granule-and-match-all-tag.cpp (19669 of 70430)

Pre-merge checks buildbot does not support HWASAN test, so we can not see this test failure in premerge checks .
Do you mean I create another differential only containing this testcase, commit it to llvm trunk and check if sanitizer-aarch64-linux-bootstrap-hwasan(https://lab.llvm.org/buildbot/#/builders/236) will fail?

Sorry, I was asking to precommit hwasan-check-accessible with checks generated for that current state of LLVM
short-granule-and-match-all-tag.cpp should stay in the main patch

[Enna1]

update

[Enna1]

update

compiler-rt/test/hwasan/TestCases/short-granule-and-match-all-tag.cpp

+// RUN: %clang_hwasan -mllvm -hwasan-match-all-tag=0 %s -o %t && %run %t
+
+#include <sanitizer/hwasan_interface.h>
+#include <stdlib.h>
+
+int main() {
+  __hwasan_enable_allocator_tagging();
+  char *x = (char *)malloc(40);
+  char volatile z = *x;
+  free(x);
+  return 0;
+}