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42 lines
1.3 KiB
42 lines
1.3 KiB
4 months ago
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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// This test computes a checksum of the data (all but the last 4 bytes),
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// and then compares the last 4 bytes with the computed value.
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// A fuzzer with cmp traces is expected to defeat this check.
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#include <cstdint>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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// A modified jenkins_one_at_a_time_hash initialized by non-zero,
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// so that simple_hash(0) != 0. See also
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// https://en.wikipedia.org/wiki/Jenkins_hash_function
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static uint32_t simple_hash(const uint8_t *Data, size_t Size) {
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uint32_t Hash = 0x12039854;
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for (uint32_t i = 0; i < Size; i++) {
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Hash += Data[i];
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Hash += (Hash << 10);
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Hash ^= (Hash >> 6);
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}
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Hash += (Hash << 3);
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Hash ^= (Hash >> 11);
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Hash += (Hash << 15);
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return Hash;
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}
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
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if (Size < 14)
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return 0;
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uint32_t Hash = simple_hash(&Data[0], Size - 4);
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uint32_t Want = reinterpret_cast<const uint32_t *>(&Data[Size - 4])[0];
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if (Hash != Want)
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return 0;
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fprintf(stderr, "BINGO; simple_hash defeated: %x == %x\n", (unsigned int)Hash,
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(unsigned int)Want);
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exit(1);
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return 0;
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}
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