[libFuzzer] Fix Load test.

[mpividori]

Summary

We should ensure the size of the variable a is 8 bytes. Otherwise, this generates a stack buffer overflow inside the memcpy call in 32 bits machines. (We write more bytes than the size of a, when it is 4 bytes).

[kcc]

LGTM

llvm/trunk/lib/Fuzzer/test/LoadTest.cpp

 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 
 // Simple test for a fuzzer: find interesting value of array index.
 #include <assert.h>
 #include <cstdint>
 #include <cstring>
 #include <cstddef>
 #include <iostream>
 
 static volatile int Sink;
 const int kArraySize = 1234567;
 int array[kArraySize];
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
   if (Size < 8) return 0;
-  size_t a = 0;
+  uint64_t a = 0;
   memcpy(&a, Data, 8);
   Sink = array[a % (kArraySize + 1)];
   return 0;
 }