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.
117 lines
3.3 KiB
C
117 lines
3.3 KiB
C
/*
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* Copyright (c) 2016-2020, 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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#include "fuzz_data_producer.h"
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static size_t const kBufSize = ZSTD_BLOCKSIZE_MAX;
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static ZSTD_DStream *dstream = NULL;
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static void* buf = NULL;
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uint32_t seed;
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static ZSTD_outBuffer makeOutBuffer(FUZZ_dataProducer_t *producer, uint32_t min)
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{
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ZSTD_outBuffer buffer = { buf, 0, 0 };
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buffer.size = (FUZZ_dataProducer_uint32Range(producer, min, kBufSize));
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FUZZ_ASSERT(buffer.size <= kBufSize);
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if (buffer.size == 0) {
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buffer.dst = NULL;
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}
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return buffer;
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}
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static ZSTD_inBuffer makeInBuffer(const uint8_t **src, size_t *size,
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FUZZ_dataProducer_t *producer,
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uint32_t min)
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{
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ZSTD_inBuffer buffer = { *src, 0, 0 };
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FUZZ_ASSERT(*size > 0);
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buffer.size = (FUZZ_dataProducer_uint32Range(producer, min, *size));
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FUZZ_ASSERT(buffer.size <= *size);
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*src += buffer.size;
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*size -= buffer.size;
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if (buffer.size == 0) {
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buffer.src = NULL;
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}
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return buffer;
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}
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int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
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{
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/* Give a random portion of src data to the producer, to use for
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parameter generation. The rest will be used for (de)compression */
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FUZZ_dataProducer_t *producer = FUZZ_dataProducer_create(src, size);
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/* Guarantee forward progress by refusing to generate 2 zero sized
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* buffers in a row. */
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int prevInWasZero = 0;
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int prevOutWasZero = 0;
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int stableOutBuffer;
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ZSTD_outBuffer out;
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size = FUZZ_dataProducer_reserveDataPrefix(producer);
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/* Allocate all buffers and contexts if not already allocated */
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if (!buf) {
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buf = FUZZ_malloc(kBufSize);
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}
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if (!dstream) {
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dstream = ZSTD_createDStream();
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FUZZ_ASSERT(dstream);
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} else {
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FUZZ_ZASSERT(ZSTD_DCtx_reset(dstream, ZSTD_reset_session_only));
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}
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stableOutBuffer = FUZZ_dataProducer_uint32Range(producer, 0, 10) == 5;
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if (stableOutBuffer) {
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FUZZ_ZASSERT(ZSTD_DCtx_setParameter(dstream, ZSTD_d_stableOutBuffer, 1));
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out.dst = buf;
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out.size = kBufSize;
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out.pos = 0;
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}
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while (size > 0) {
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ZSTD_inBuffer in = makeInBuffer(&src, &size, producer, prevInWasZero ? 1 : 0);
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prevInWasZero = in.size == 0;
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while (in.pos != in.size) {
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if (!stableOutBuffer || prevOutWasZero || FUZZ_dataProducer_uint32Range(producer, 0, 100) == 55) {
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out = makeOutBuffer(producer, prevOutWasZero ? 1 : 0);
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}
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prevOutWasZero = out.size == 0;
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size_t const rc = ZSTD_decompressStream(dstream, &out, &in);
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if (ZSTD_isError(rc)) goto error;
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}
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}
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error:
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#ifndef STATEFUL_FUZZING
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ZSTD_freeDStream(dstream); dstream = NULL;
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#endif
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FUZZ_dataProducer_free(producer);
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return 0;
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}
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