[HWASAN] Modify HwasanAllocate to set the size to 1 if requested size is 0

[kstoimenov]

Summary

This should keep it consistent with LSAN and ASAN,

[MaskRay]

An alternative is to do if (orig_size == 0) orig_size = 1 in HwasanAllocate. asan/lsan do this.

[kstoimenov]

Make size 1 if 0.

[kstoimenov]

Revert chang in Metadata::IsAllocated.

[MaskRay]

I know that hwasan x86-64 needs involved setup. Wish that is documented somewhere (e.g. https://github.com/google/sanitizers/wiki) so that interested folks (like I) can play with it :)

[kstoimenov]

Reverted test.

[kstoimenov]

In D143438#4108290, @MaskRay wrote:

An alternative is to do if (orig_size == 0) orig_size = 1 in HwasanAllocate. asan/lsan do this.

Good point. I changed that to make it consistent with ASAN and LSAN.

[vitalybuka]

compiler-rt/lib/hwasan/hwasan_allocator.cpp

166

168

same

[kstoimenov]

Updated title and added UNLIKELY.

[kstoimenov]

Need to fix 2 tests that this patch broke.

compiler-rt/lib/hwasan/hwasan_allocator.cpp

static uptr TaggedSize(uptr size) {
   if (!size) size = 1;
   uptr new_size = RoundUpTo(size, kShadowAlignment);
   CHECK_GE(new_size, size);
   return new_size;
 }
 
 static void *HwasanAllocate(StackTrace *stack, uptr orig_size, uptr alignment,
                             bool zeroise) {
+  // Keep this consistent with LSAN and ASAN behavior.
+  if (orig_size == 0)
+    orig_size = 1;
   if (orig_size > kMaxAllowedMallocSize) {
     if (AllocatorMayReturnNull()) {
       Report("WARNING: HWAddressSanitizer failed to allocate 0x%zx bytes\n",
              orig_size);
       return nullptr;
     }
     ReportAllocationSizeTooBig(orig_size, kMaxAllowedMallocSize, stack);
   }
   if (UNLIKELY(IsRssLimitExceeded())) {

compiler-rt/test/lsan/TestCases/malloc_zero.c

 // RUN: %clang_lsan %s -o %t
 // RUN: %env_lsan_opts=use_stacks=0 not %run %t 2>&1 | FileCheck %s
 
-// Fixme: remove once test passes with hwasan
-// UNSUPPORTED: hwasan
-
 /// Fails when only leak sanitizer is enabled
 // UNSUPPORTED: arm-linux, armhf-linux
 
 #include <stdio.h>
 #include <stdlib.h>
 
 // CHECK: {{Leak|Address}}Sanitizer: detected memory leaks
 // CHECK: {{Leak|Address}}Sanitizer: 1 byte(s) leaked in 1 allocation(s).
 
 int main() {
   // The behavior of malloc(0) is implementation-defined.
   char *p = malloc(0);
   fprintf(stderr, "zero: %p\n", p);
   p = 0;
 }