42 lines · cpp
1// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.2// See https://llvm.org/LICENSE.txt for license information.3// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception4 5// This test computes a checksum of the data (all but the last 4 bytes),6// and then compares the last 4 bytes with the computed value.7// A fuzzer with cmp traces is expected to defeat this check.8#include <cstdint>9#include <cstdio>10#include <cstdlib>11#include <cstring>12 13// A modified jenkins_one_at_a_time_hash initialized by non-zero,14// so that simple_hash(0) != 0. See also15// https://en.wikipedia.org/wiki/Jenkins_hash_function16static uint32_t simple_hash(const uint8_t *Data, size_t Size) {17 uint32_t Hash = 0x12039854;18 for (uint32_t i = 0; i < Size; i++) {19 Hash += Data[i];20 Hash += (Hash << 10);21 Hash ^= (Hash >> 6);22 }23 Hash += (Hash << 3);24 Hash ^= (Hash >> 11);25 Hash += (Hash << 15);26 return Hash;27}28 29extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {30 if (Size < 14)31 return 0;32 33 uint32_t Hash = simple_hash(&Data[0], Size - 4);34 uint32_t Want = reinterpret_cast<const uint32_t *>(&Data[Size - 4])[0];35 if (Hash != Want)36 return 0;37 fprintf(stderr, "BINGO; simple_hash defeated: %x == %x\n", (unsigned int)Hash,38 (unsigned int)Want);39 exit(1);40 return 0;41}42