[libFuzzer] don't write the test unit when a leak is detected (since we don't know which unit causes the leak)

llvm-svn: 259731

llvm/lib/Fuzzer/FuzzerLoop.cpp

@@ -75,6 +75,7 @@ void Fuzzer::StaticDeathCallback() {
 }
 
 void Fuzzer::DeathCallback() {
+  if (!CurrentUnitSize) return;
   Printf("DEATH:\n");
   if (CurrentUnitSize <= kMaxUnitSizeToPrint) {
     PrintHexArray(CurrentUnitData, CurrentUnitSize, "\n");

llvm/lib/Fuzzer/test/CMakeLists.txt

@@ -20,6 +20,7 @@ set(Tests
   FullCoverageSetTest
   InitializeTest
   MemcmpTest
+  LeakTest
   NullDerefTest
   RepeatedMemcmp
   SimpleCmpTest

llvm/lib/Fuzzer/test/LeakTest.cpp

@@ -0,0 +1,11 @@
+// Test with a leak.
+#include <cstdint>
+#include <cstddef>
+
+static volatile void *Sink;
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  Sink = new int;
+  return 0;
+}
+

llvm/lib/Fuzzer/test/fuzzer.test

@@ -57,3 +57,6 @@ SINGLE_INPUTS: LLVMFuzzer-SimpleTest: Running 2 inputs.
 SINGLE_INPUTS: aaa:
 SINGLE_INPUTS: bbb:
 
+RUN: LLVMFuzzer-LeakTest -runs=10 2>&1 | FileCheck %s --check-prefix=LEAK
+LEAK: ERROR: LeakSanitizer: detected memory leaks
+LEAK-NOT: DEATH: