[libFuzzer] add a test for libFuzzer+ubsan, extend the docs on using libFuzzer+ubsan

llvm-svn: 268968

1 files changed, 28 insertions, 0 deletions

diff --git a/llvm/lib/Fuzzer/test/SignedIntOverflowTest.cpp b/llvm/lib/Fuzzer/test/SignedIntOverflowTest.cpp
new file mode 100644
index 0000000..7df32ad
--- /dev/null
+++ b/llvm/lib/Fuzzer/test/SignedIntOverflowTest.cpp
@@ -0,0 +1,28 @@
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+
+// Test for signed-integer-overflow.
+#include <assert.h>
+#include <cstdint>
+#include <cstdlib>
+#include <cstddef>
+#include <iostream>
+#include <climits>
+
+static volatile int Sink;
+static int Large = INT_MAX;
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  assert(Data);
+  if (Size > 0 && Data[0] == 'H') {
+    Sink = 1;
+    if (Size > 1 && Data[1] == 'i') {
+      Sink = 2;
+      if (Size > 2 && Data[2] == '!') {
+        Large++;  // int overflow.
+      }
+    }
+  }
+  return 0;
+}
+