[hwasan] State correct PC in first error message.

[fmayer]

Summary

We would put the return address there, rather than the fault address.

[fmayer]

format

[eugenis]

LGTM

[CarlosAlbertoEnciso]

@fmayer : It looks like your changes may be are causing test issues:

https://lab.llvm.org/buildbot/#/builders/37/builds/6011

Failed Tests (2):

HWAddressSanitizer-x86_64 :: TestCases/double-free.c
HWAddressSanitizer-x86_64 :: TestCases/use-after-free.c

Thanks

compiler-rt/lib/hwasan/hwasan_report.cpp

static void PrintTagsAroundAddr(tag_t *tag_ptr) {
   });
   Printf(
       "See "
       "https://clang.llvm.org/docs/"
       "HardwareAssistedAddressSanitizerDesign.html#short-granules for a "
       "description of short granule tags\n");
 }
 
+uptr GetTopPc(StackTrace* stack) {
+  return stack->size ? StackTrace::GetPreviousInstructionPc(stack->trace[0]) : 0;
+}
+
 void ReportInvalidFree(StackTrace *stack, uptr tagged_addr) {
   ScopedReport R(flags()->halt_on_error);
 
   uptr untagged_addr = UntagAddr(tagged_addr);
   tag_t ptr_tag = GetTagFromPointer(tagged_addr);
   tag_t *tag_ptr = reinterpret_cast<tag_t*>(MemToShadow(untagged_addr));
   tag_t mem_tag = *tag_ptr;
   Decorator d;
   Printf("%s", d.Error());
-  uptr pc = stack->size ? stack->trace[0] : 0;
+  uptr pc = GetTopPc(stack);
   const char *bug_type = "invalid-free";
   const Thread *thread = GetCurrentThread();
   if (thread) {
     Report("ERROR: %s: %s on address %p at pc %p on thread T%zd\n",
            SanitizerToolName, bug_type, untagged_addr, pc, thread->unique_id());
   } else {
     Report("ERROR: %s: %s on address %p at pc %p on unknown thread\n",
            SanitizerToolName, bug_type, untagged_addr, pc);
void ReportTagMismatch(StackTrace *stack, uptr tagged_addr, uptr access_size,
   SavedStackAllocations current_stack_allocations(
       GetCurrentThread()->stack_allocations());
 
   Decorator d;
   Printf("%s", d.Error());
   uptr untagged_addr = UntagAddr(tagged_addr);
   // TODO: when possible, try to print heap-use-after-free, etc.
   const char *bug_type = "tag-mismatch";
-  uptr pc = stack->size ? stack->trace[0] : 0;
+  uptr pc = GetTopPc(stack);
   Report("ERROR: %s: %s on address %p at pc %p\n", SanitizerToolName, bug_type,
          untagged_addr, pc);
 
   Thread *t = GetCurrentThread();
 
   sptr offset =
       __hwasan_test_shadow(reinterpret_cast<void *>(tagged_addr), access_size);
   CHECK(offset >= 0 && offset < static_cast<sptr>(access_size));

compiler-rt/test/hwasan/TestCases/double-free.c

 // RUN: %clang_hwasan %s -o %t && not %run %t 2>&1 | FileCheck %s
 
 // REQUIRES: stable-runtime
 
 #include <stdlib.h>
 #include <stdio.h>
 #include <sanitizer/hwasan_interface.h>
 
 int main() {
   __hwasan_enable_allocator_tagging();
   char * volatile x = (char*)malloc(40);
   free(x);
   free(x);
-// CHECK: ERROR: HWAddressSanitizer: invalid-free on address {{.*}} at pc {{.*}} on thread T{{[0-9]+}}
+// CHECK: ERROR: HWAddressSanitizer: invalid-free on address {{.*}} at pc {{[0x]+}}[[PC:.*]] on thread T{{[0-9]+}}
 // CHECK: tags: [[PTR_TAG:..]]/[[MEM_TAG:..]] (ptr/mem)
+// CHECK: #0 {{[0x]+}}{{.*}}[[PC]] in free
 // CHECK: freed by thread {{.*}} here:
 // CHECK: previously allocated here:
 // CHECK: Memory tags around the buggy address (one tag corresponds to 16 bytes):
 // CHECK: =>{{.*}}[[MEM_TAG]]
   fprintf(stderr, "DONE\n");
   __hwasan_disable_allocator_tagging();
 // CHECK-NOT: DONE
 }

compiler-rt/test/hwasan/TestCases/use-after-free.c

int main() {
   __hwasan_enable_allocator_tagging();
   char * volatile x = (char*)malloc(10);
   free(x);
   __hwasan_disable_allocator_tagging();
   fprintf(stderr, ISREAD ? "Going to do a READ\n" : "Going to do a WRITE\n");
   // CHECK: Going to do a [[TYPE:[A-Z]*]]
   int r = 0;
   if (ISREAD) r = x[5]; else x[5] = 42;  // should be on the same line.
+  // CHECK: ERROR: HWAddressSanitizer: tag-mismatch on address {{.*}} at pc {{[0x]+}}[[PC:.*]]
   // CHECK: [[TYPE]] of size 1 at {{.*}} tags: [[PTR_TAG:[0-9a-f][0-9a-f]]]/[[MEM_TAG:[0-9a-f][0-9a-f]]] (ptr/mem)
-  // CHECK: #{{[0-9]}} {{.*}} in main {{.*}}use-after-free.c:[[@LINE-2]]
+  // CHECK: #{{[0-9]}} {{[0-9]+}}{{.*}}[[PC]] in main {{.*}}use-after-free.c:[[@LINE-3]]
   // Offset is 5 or 11 depending on left/right alignment.
   // CHECK: is a small unallocated heap chunk; size: 32 offset: {{5|11}}
   // CHECK: Cause: use-after-free
   // CHECK: is located 5 bytes inside of 10-byte region
   //
   // CHECK: freed by thread {{.*}} here:
   // CHECK: #0 {{.*}} in {{.*}}free{{.*}} {{.*}}hwasan_allocation_functions.cpp
-  // CHECK: #1 {{.*}} in main {{.*}}use-after-free.c:[[@LINE-15]]
+  // CHECK: #1 {{.*}} in main {{.*}}use-after-free.c:[[@LINE-16]]
 
   // CHECK: previously allocated here:
   // CHECK: #0 {{.*}} in {{.*}}malloc{{.*}} {{.*}}hwasan_allocation_functions.cpp
-  // CHECK: #1 {{.*}} in main {{.*}}use-after-free.c:[[@LINE-20]]
+  // CHECK: #1 {{.*}} in main {{.*}}use-after-free.c:[[@LINE-21]]
   // CHECK: Memory tags around the buggy address (one tag corresponds to 16 bytes):
   // CHECK: =>{{.*}}[[MEM_TAG]]
   // CHECK: SUMMARY: HWAddressSanitizer: tag-mismatch
   return r;
 }