[libFuzzer] Report at most one crash per input.

Summary:
Fixes https://github.com/google/sanitizers/issues/788/, a deadlock
caused by multiple crashes happening at the same time.  Before printing
a crash report, we now test and set an atomic flag.  If the flag was
already set, the crash handler returns immediately.

Reviewers: kcc

Reviewed By: kcc

Subscribers: llvm-commits, kubamracek

Differential Revision: https://reviews.llvm.org/D46277

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@331310 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/fuzzer/FuzzerLoop.cpp b/lib/fuzzer/FuzzerLoop.cpp
index cd835bea5..7a26370b3 100644
--- a/lib/fuzzer/FuzzerLoop.cpp
+++ b/lib/fuzzer/FuzzerLoop.cpp
@@ -228,6 +228,9 @@ void Fuzzer::StaticFileSizeExceedCallback() {
 }
 
 void Fuzzer::CrashCallback() {
+  if (EF->__sanitizer_acquire_crash_state &&
+      !EF->__sanitizer_acquire_crash_state())
+    return;
   Printf("==%lu== ERROR: libFuzzer: deadly signal\n", GetPid());
   if (EF->__sanitizer_print_stack_trace)
     EF->__sanitizer_print_stack_trace();
@@ -243,6 +246,9 @@ void Fuzzer::CrashCallback() {
 void Fuzzer::ExitCallback() {
   if (!RunningCB)
     return; // This exit did not come from the user callback
+  if (EF->__sanitizer_acquire_crash_state &&
+      !EF->__sanitizer_acquire_crash_state())
+    return;
   Printf("==%lu== ERROR: libFuzzer: fuzz target exited\n", GetPid());
   if (EF->__sanitizer_print_stack_trace)
     EF->__sanitizer_print_stack_trace();
@@ -282,6 +288,9 @@ void Fuzzer::AlarmCallback() {
   if (Options.Verbosity >= 2)
     Printf("AlarmCallback %zd\n", Seconds);
   if (Seconds >= (size_t)Options.UnitTimeoutSec) {
+    if (EF->__sanitizer_acquire_crash_state &&
+        !EF->__sanitizer_acquire_crash_state())
+      return;
     Printf("ALARM: working on the last Unit for %zd seconds\n", Seconds);
     Printf("       and the timeout value is %d (use -timeout=N to change)\n",
            Options.UnitTimeoutSec);
@@ -297,6 +306,9 @@ void Fuzzer::AlarmCallback() {
 }
 
 void Fuzzer::RssLimitCallback() {
+  if (EF->__sanitizer_acquire_crash_state &&
+      !EF->__sanitizer_acquire_crash_state())
+    return;
   Printf(
       "==%lu== ERROR: libFuzzer: out-of-memory (used: %zdMb; limit: %zdMb)\n",
       GetPid(), GetPeakRSSMb(), Options.RssLimitMb);