[hwasan] Add entire report to abort message on Android.

[eugenis]

Summary

When reporting a fatal error, collect and add the entire report text to
android_set_abort_message so that it can be found in the tombstone.

[kcc]

compiler-rt/lib/hwasan/hwasan_report.cc

68

why not InternalScopedString ?

[eugenis]

compiler-rt/lib/hwasan/hwasan_report.cc

68

I don't like InternalScopedString. Its append method truncates the string instead of resizing the storage, and also does unnecessary format string parsing.

[kcc]

compiler-rt/lib/hwasan/hwasan_report.cc

68

ack.
I'd prefer to add append() method to InternalMmapVector then and use it here

[kcc]

LGTM

compiler-rt/lib/hwasan/hwasan_report.cc

68

actually, up to you.

compiler-rt/lib/hwasan/hwasan.h

 
 void HwasanTSDInit();
 void HwasanTSDThreadInit();
 
 void HwasanOnDeadlySignal(int signo, void *info, void *context);
 
 void UpdateMemoryUsage();
 
+void AppendToErrorMessageBuffer(const char *buffer);
+
 }  // namespace __hwasan
 
 #define HWASAN_MALLOC_HOOK(ptr, size)       \
   do {                                    \
     if (&__sanitizer_malloc_hook) {       \
       __sanitizer_malloc_hook(ptr, size); \
     }                                     \
     RunMallocHooks(ptr, size);            \

compiler-rt/lib/hwasan/hwasan.cc

void __hwasan_init() {
 
   __hwasan_shadow_init();
 
   InitThreads();
   hwasanThreadList().CreateCurrentThread();
 
   MadviseShadow();
 
+  SetPrintfAndReportCallback(AppendToErrorMessageBuffer);
   // This may call libc -> needs initialized shadow.
   AndroidLogInit();
 
   InitializeInterceptors();
   InstallDeadlySignalHandlers(HwasanOnDeadlySignal);
   InstallAtExitHandler(); // Needs __cxa_atexit interceptor.
 
   Symbolizer::GetOrInit()->AddHooks(EnterSymbolizer, ExitSymbolizer);

compiler-rt/lib/hwasan/hwasan_linux.cc

static bool HwasanOnSIGTRAP(int signo, siginfo_t *info, ucontext_t *uc) {
 
   InternalMmapVector<BufferedStackTrace> stack_buffer(1);
   BufferedStackTrace *stack = stack_buffer.data();
   stack->Reset();
   SignalContext sig{info, uc};
   GetStackTrace(stack, kStackTraceMax, StackTrace::GetNextInstructionPc(sig.pc),
                 sig.bp, uc, common_flags()->fast_unwind_on_fatal);
 
-  ReportTagMismatch(stack, ai.addr, ai.size, ai.is_store);
-
   ++hwasan_report_count;
-  if (flags()->halt_on_error || !ai.recover)
-    Die();
+
+  bool fatal = flags()->halt_on_error || !ai.recover;
+  ReportTagMismatch(stack, ai.addr, ai.size, ai.is_store, fatal);
 
 #if defined(__aarch64__)
   uc->uc_mcontext.pc += 4;
 #elif defined(__x86_64__)
 #else
 # error Unsupported architecture
 #endif
   return true;

compiler-rt/lib/hwasan/hwasan_report.h

 
 #include "sanitizer_common/sanitizer_internal_defs.h"
 #include "sanitizer_common/sanitizer_stacktrace.h"
 
 namespace __hwasan {
 
 void ReportStats();
 void ReportTagMismatch(StackTrace *stack, uptr addr, uptr access_size,
-                       bool is_store);
+                       bool is_store, bool fatal);
 void ReportInvalidFree(StackTrace *stack, uptr addr);
 
 void ReportAtExitStatistics();
 
 
 }  // namespace __hwasan
 
 #endif  // HWASAN_REPORT_H

compiler-rt/lib/hwasan/hwasan_report.cc

 #include "sanitizer_common/sanitizer_stackdepot.h"
 #include "sanitizer_common/sanitizer_stacktrace_printer.h"
 #include "sanitizer_common/sanitizer_symbolizer.h"
 
 using namespace __sanitizer;
 
 namespace __hwasan {
 
+class ScopedReport {
+ public:
+  ScopedReport(bool fatal = false) : error_message_(1), fatal(fatal) {
+    BlockingMutexLock lock(&error_message_lock_);
+    error_message_ptr_ = fatal ? &error_message_ : nullptr;
+  }
+
+  ~ScopedReport() {
+    BlockingMutexLock lock(&error_message_lock_);
+    if (fatal) {
+      SetAbortMessage(error_message_.data());
+      Die();
+    }
+    error_message_ptr_ = nullptr;
+  }
+
+  static void MaybeAppendToErrorMessage(const char *msg) {
+    BlockingMutexLock lock(&error_message_lock_);
+    if (!error_message_ptr_)
+      return;
+    uptr len = internal_strlen(msg);
+    uptr old_size = error_message_ptr_->size();
+    error_message_ptr_->resize(old_size + len);
+    // overwrite old trailing '\0', keep new trailing '\0' untouched.
+    internal_memcpy(&(*error_message_ptr_)[old_size - 1], msg, len);
+  }
+ private:
+  ScopedErrorReportLock error_report_lock_;
+  InternalMmapVector<char> error_message_;
+  bool fatal;
+
+  static InternalMmapVector<char> *error_message_ptr_;
+  static BlockingMutex error_message_lock_;
+};
+
+InternalMmapVector<char> *ScopedReport::error_message_ptr_;
+BlockingMutex ScopedReport::error_message_lock_;
+
+// If there is an active ScopedReport, append to its error message.
+void AppendToErrorMessageBuffer(const char *buffer) {
+  ScopedReport::MaybeAppendToErrorMessage(buffer);
+}
+
 static StackTrace GetStackTraceFromId(u32 id) {
   CHECK(id);
   StackTrace res = StackDepotGet(id);
   CHECK(res.trace);
   return res;
 }
 
 // A RAII object that holds a copy of the current thread stack ring buffer.
for (uptr i = 0; i < row_len; i++) {
       s.append("%s", row + i == tag_ptr ? "]" : " ");
     }
     s.append("%s\n", row == center_row_beg ? "<=" : "  ");
   }
   Printf("%s", s.data());
 }
 
 void ReportInvalidFree(StackTrace *stack, uptr tagged_addr) {
-  ScopedErrorReportLock l;
+  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;
   const char *bug_type = "invalid-free";
   Report("ERROR: %s: %s on address %p at pc %p\n", SanitizerToolName, bug_type,
          untagged_addr, pc);
   Printf("%s", d.Access());
   Printf("tags: %02x/%02x (ptr/mem)\n", ptr_tag, mem_tag);
   Printf("%s", d.Default());
 
   stack->Print();
 
   PrintAddressDescription(tagged_addr, 0, nullptr);
 
   PrintTagsAroundAddr(tag_ptr);
 
   ReportErrorSummary(bug_type, stack);
-  Die();
 }
 
 void ReportTagMismatch(StackTrace *stack, uptr tagged_addr, uptr access_size,
-                       bool is_store) {
-  ScopedErrorReportLock l;
+                       bool is_store, bool fatal) {
+  ScopedReport R(fatal);
   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";

compiler-rt/test/hwasan/TestCases/abort-message-android.cc

+// RUN: %clangxx_hwasan -DERR=1 %s -o %t && not %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_hwasan -DERR=2 %s -o %t && not %run %t 2>&1 | FileCheck %s
+// REQUIRES: android
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <sanitizer/hwasan_interface.h>
+
+__attribute__((no_sanitize("hwaddress")))
+extern "C" void android_set_abort_message(const char *msg) {
+  fprintf(stderr, "== abort message start\n%s\n== abort message end\n", msg);
+}
+
+int main() {
+  __hwasan_enable_allocator_tagging();
+  char *volatile p = (char *)malloc(16);
+  if (ERR==1) {
+    p[16] = 1;
+  } else {
+    free(p);
+    free(p);
+  }
+  // CHECK: ERROR: HWAddressSanitizer:
+  // CHECK: == abort message start
+  // CHECK: ERROR: HWAddressSanitizer:
+  // CHECK: == abort message end
+}