5717bd39ee
When the output buffer is `NULL` with size 0, but the frame content size is non-zero, we will write to the NULL pointer because our bounds check underflowed. This was exposed by a recent PR that allowed an empty frame into the single-pass shortcut in streaming mode. * Fix the bug. * Fix another NULL dereference in zstd-v1. * Overflow checks in 32-bit mode. * Add a dedicated test. * Expose the bug in the dedicated simple_decompress fuzzer. * Switch all mallocs in fuzzers to return NULL for size=0. * Fix a new timeout in a fuzzer. Neither clang nor gcc show a decompression speed regression on x86-64. On x86-32 clang is slightly positive and gcc loses 2.5% of speed. Credit to OSS-Fuzz.
50 lines
1.3 KiB
C
50 lines
1.3 KiB
C
/**
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* Copyright (c) 2016-2020, Yann Collet, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under both the BSD-style license (found in the
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* LICENSE file in the root directory of this source tree) and the GPLv2 (found
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* in the COPYING file in the root directory of this source tree).
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* You may select, at your option, one of the above-listed licenses.
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*/
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/**
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* This fuzz target attempts to decompress the fuzzed data with the simple
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* decompression function to ensure the decompressor never crashes.
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*/
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#define ZSTD_STATIC_LINKING_ONLY
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#include <stddef.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include "fuzz_helpers.h"
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#include "zstd.h"
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static ZSTD_DCtx *dctx = NULL;
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static void* rBuf = NULL;
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static size_t bufSize = 0;
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int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
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{
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size_t const neededBufSize = ZSTD_BLOCKSIZE_MAX;
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/* Allocate all buffers and contexts if not already allocated */
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if (neededBufSize > bufSize) {
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free(rBuf);
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rBuf = FUZZ_malloc(neededBufSize);
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bufSize = neededBufSize;
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}
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if (!dctx) {
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dctx = ZSTD_createDCtx();
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FUZZ_ASSERT(dctx);
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}
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ZSTD_decompressBegin(dctx);
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ZSTD_decompressBlock(dctx, rBuf, neededBufSize, src, size);
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#ifndef STATEFUL_FUZZING
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ZSTD_freeDCtx(dctx); dctx = NULL;
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#endif
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return 0;
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}
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