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/*
* Copyright (c) 2016-2020, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
* You may select, at your option, one of the above-listed licenses.
*/
/**
* This fuzz target performs a zstd round-trip test by generating an arbitrary
* array of sequences, generating the associated source buffer, calling
* ZSTD_compressSequences(), and then decompresses and compares the result with
* the original generated source buffer.
*/
#define ZSTD_STATIC_LINKING_ONLY
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include "fuzz_helpers.h"
#include "zstd_helpers.h"
#include "fuzz_data_producer.h"
static ZSTD_CCtx *cctx = NULL;
static ZSTD_DCtx *dctx = NULL;
static void* literalsBuffer = NULL;
static void* generatedSrc = NULL;
static ZSTD_Sequence* generatedSequences = NULL;
#define ZSTD_FUZZ_GENERATED_SRC_MAXSIZE (1 << 20) /* Allow up to 1MB generated data */
#define ZSTD_FUZZ_MATCHLENGTH_MAXSIZE (1 << 18) /* Allow up to 256KB matches */
#define ZSTD_FUZZ_GENERATED_DICT_MAXSIZE (1 << 18) /* Allow up to a 256KB dict */
#define ZSTD_FUZZ_GENERATED_LITERALS_SIZE (1 << 18) /* Fixed size 256KB literals buffer */
#define ZSTD_FUZZ_MAX_NBSEQ (1 << 17) /* Maximum of 128K sequences */
/* Deterministic random number generator */
#define FUZZ_RDG_rotl32(x,r) ((x << r) | (x >> (32 - r)))
static uint32_t FUZZ_RDG_rand(uint32_t* src)
{
static const uint32_t prime1 = 2654435761U;
static const uint32_t prime2 = 2246822519U;
uint32_t rand32 = *src;
rand32 *= prime1;
rand32 ^= prime2;
rand32 = FUZZ_RDG_rotl32(rand32, 13);
*src = rand32;
return rand32 >> 5;
}
/* Make a pseudorandom string - this simple function exists to avoid
* taking a dependency on datagen.h to have RDG_genBuffer().
*/
static char *generatePseudoRandomString(char *str, size_t size) {
const char charset[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJK1234567890!@#$^&*()_";
uint32_t seed = 0;
if (size) {
for (size_t n = 0; n < size; n++) {
int key = FUZZ_RDG_rand(&seed) % (int) (sizeof charset - 1);
str[n] = charset[key];
}
}
return str;
}
/* Returns size of source buffer */
static size_t decodeSequences(void* dst, size_t nbSequences,
size_t literalsSize, const void* dict, size_t dictSize) {
const uint8_t* litPtr = literalsBuffer;
const uint8_t* const litBegin = literalsBuffer;
const uint8_t* const litEnd = literalsBuffer + literalsSize;
const uint8_t* dictPtr = dict;
uint8_t* op = dst;
const uint8_t* const oend = dst + ZSTD_FUZZ_GENERATED_SRC_MAXSIZE;
size_t generatedSrcBufferSize = 0;
size_t bytesWritten = 0;
uint32_t lastLLSize;
for (size_t i = 0; i < nbSequences; ++i) {
FUZZ_ASSERT(generatedSequences[i].matchLength != 0);
FUZZ_ASSERT(generatedSequences[i].offset != 0);
if (litPtr + generatedSequences[i].litLength > litEnd) {
litPtr = litBegin;
}
ZSTD_memcpy(op, litPtr, generatedSequences[i].litLength);
bytesWritten += generatedSequences[i].litLength;
op += generatedSequences[i].litLength;
litPtr += generatedSequences[i].litLength;
FUZZ_ASSERT(generatedSequences[i].offset != 0);
/* Copy over the match */
{ size_t matchLength = generatedSequences[i].matchLength;
size_t j = 0;
size_t k = 0;
if (dictSize != 0) {
if (generatedSequences[i].offset > bytesWritten) {
/* Offset goes into the dictionary */
size_t offsetFromEndOfDict = generatedSequences[i].offset - bytesWritten;
for (; k < offsetFromEndOfDict && k < matchLength; ++k) {
op[k] = dictPtr[dictSize - offsetFromEndOfDict + k];
}
matchLength -= k;
op += k;
}
}
for (; j < matchLength; ++j) {
op[j] = op[j-(int)generatedSequences[i].offset];
}
op += j;
FUZZ_ASSERT(generatedSequences[i].matchLength == j + k);
bytesWritten += generatedSequences[i].matchLength;
}
}
generatedSrcBufferSize = bytesWritten;
FUZZ_ASSERT(litPtr <= litEnd);
lastLLSize = (uint32_t)(litEnd - litPtr);
if (lastLLSize <= oend - op) {
ZSTD_memcpy(op, litPtr, lastLLSize);
generatedSrcBufferSize += lastLLSize;
}
return generatedSrcBufferSize;
}
/* Returns nb sequences generated
* TODO: Add repcode fuzzing once we support repcode match splits
*/
static size_t generateRandomSequences(FUZZ_dataProducer_t* producer,
size_t literalsSizeLimit, size_t dictSize,
size_t windowLog) {
uint32_t bytesGenerated = 0;
uint32_t nbSeqGenerated = 0;
uint32_t litLength;
uint32_t matchLength;
uint32_t matchBound;
uint32_t offset;
uint32_t offsetBound;
uint32_t repCode = 0;
uint32_t isFirstSequence = 1;
uint32_t windowSize = 1 << windowLog;
while (nbSeqGenerated < ZSTD_FUZZ_MAX_NBSEQ
&& bytesGenerated < ZSTD_FUZZ_GENERATED_SRC_MAXSIZE
&& !FUZZ_dataProducer_empty(producer)) {
matchBound = ZSTD_FUZZ_MATCHLENGTH_MAXSIZE;
litLength = isFirstSequence && dictSize == 0 ? FUZZ_dataProducer_uint32Range(producer, 1, literalsSizeLimit)
: FUZZ_dataProducer_uint32Range(producer, 0, literalsSizeLimit);
bytesGenerated += litLength;
if (bytesGenerated > ZSTD_FUZZ_GENERATED_SRC_MAXSIZE) {
break;
}
offsetBound = bytesGenerated > windowSize ? windowSize : bytesGenerated + dictSize;
offset = FUZZ_dataProducer_uint32Range(producer, 1, offsetBound);
if (dictSize > 0 && bytesGenerated <= windowSize) {
/* Prevent match length from being such that it would be associated with an offset too large
* from the decoder's perspective. If not possible (match would be too small),
* then reduce the offset if necessary.
*/
size_t bytesToReachWindowSize = windowSize - bytesGenerated;
if (bytesToReachWindowSize < ZSTD_MINMATCH_MIN) {
uint32_t newOffsetBound = offsetBound > windowSize ? windowSize : offsetBound;
offset = FUZZ_dataProducer_uint32Range(producer, 1, newOffsetBound);
} else {
matchBound = bytesToReachWindowSize > ZSTD_FUZZ_MATCHLENGTH_MAXSIZE ?
ZSTD_FUZZ_MATCHLENGTH_MAXSIZE : bytesToReachWindowSize;
}
}
matchLength = FUZZ_dataProducer_uint32Range(producer, ZSTD_MINMATCH_MIN, matchBound);
bytesGenerated += matchLength;
if (bytesGenerated > ZSTD_FUZZ_GENERATED_SRC_MAXSIZE) {
break;
}
ZSTD_Sequence seq = {offset, litLength, matchLength, repCode};
generatedSequences[nbSeqGenerated++] = seq;
isFirstSequence = 0;
}
return nbSeqGenerated;
}
static size_t roundTripTest(void *result, size_t resultCapacity,
void *compressed, size_t compressedCapacity,
size_t srcSize,
const void *dict, size_t dictSize,
size_t generatedSequencesSize,
size_t wLog, unsigned cLevel, unsigned hasDict)
{
size_t cSize;
size_t dSize;
ZSTD_CDict* cdict = NULL;
ZSTD_DDict* ddict = NULL;
ZSTD_CCtx_reset(cctx, ZSTD_reset_session_and_parameters);
ZSTD_CCtx_setParameter(cctx, ZSTD_c_nbWorkers, 0);
ZSTD_CCtx_setParameter(cctx, ZSTD_c_compressionLevel, cLevel);
ZSTD_CCtx_setParameter(cctx, ZSTD_c_windowLog, wLog);
ZSTD_CCtx_setParameter(cctx, ZSTD_c_minMatch, ZSTD_MINMATCH_MIN);
ZSTD_CCtx_setParameter(cctx, ZSTD_c_validateSequences, 1);
/* TODO: Add block delim mode fuzzing */
ZSTD_CCtx_setParameter(cctx, ZSTD_c_blockDelimiters, ZSTD_sf_noBlockDelimiters);
if (hasDict) {
FUZZ_ZASSERT(ZSTD_CCtx_loadDictionary(cctx, dict, dictSize));
FUZZ_ZASSERT(ZSTD_DCtx_loadDictionary(dctx, dict, dictSize));
}
cSize = ZSTD_compressSequences(cctx, compressed, compressedCapacity,
generatedSequences, generatedSequencesSize,
generatedSrc, srcSize);
FUZZ_ZASSERT(cSize);
dSize = ZSTD_decompressDCtx(dctx, result, resultCapacity, compressed, cSize);
FUZZ_ZASSERT(dSize);
if (cdict) {
ZSTD_freeCDict(cdict);
}
if (ddict) {
ZSTD_freeDDict(ddict);
}
return dSize;
}
int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
{
void* rBuf;
size_t rBufSize;
void* cBuf;
size_t cBufSize;
size_t generatedSrcSize;
size_t nbSequences;
void* dictBuffer;
size_t dictSize = 0;
unsigned hasDict;
unsigned wLog;
int cLevel;
FUZZ_dataProducer_t *producer = FUZZ_dataProducer_create(src, size);
if (literalsBuffer == NULL) {
literalsBuffer = FUZZ_malloc(ZSTD_FUZZ_GENERATED_LITERALS_SIZE);
literalsBuffer = generatePseudoRandomString(literalsBuffer, ZSTD_FUZZ_GENERATED_LITERALS_SIZE);
}
hasDict = FUZZ_dataProducer_uint32Range(producer, 0, 1);
if (hasDict) {
dictSize = FUZZ_dataProducer_uint32Range(producer, 1, ZSTD_FUZZ_GENERATED_DICT_MAXSIZE);
dictBuffer = FUZZ_malloc(dictSize);
dictBuffer = generatePseudoRandomString(dictBuffer, dictSize);
}
/* Generate window log first so we dont generate offsets too large */
wLog = FUZZ_dataProducer_uint32Range(producer, ZSTD_WINDOWLOG_MIN, ZSTD_WINDOWLOG_MAX_32);
cLevel = FUZZ_dataProducer_int32Range(producer, -3, 22);
if (!generatedSequences) {
generatedSequences = FUZZ_malloc(sizeof(ZSTD_Sequence)*ZSTD_FUZZ_MAX_NBSEQ);
}
if (!generatedSrc) {
generatedSrc = FUZZ_malloc(ZSTD_FUZZ_GENERATED_SRC_MAXSIZE);
}
nbSequences = generateRandomSequences(producer, ZSTD_FUZZ_GENERATED_LITERALS_SIZE, dictSize, wLog);
generatedSrcSize = decodeSequences(generatedSrc, nbSequences, ZSTD_FUZZ_GENERATED_LITERALS_SIZE, dictBuffer, dictSize);
cBufSize = ZSTD_compressBound(generatedSrcSize);
cBuf = FUZZ_malloc(cBufSize);
rBufSize = generatedSrcSize;
rBuf = FUZZ_malloc(rBufSize);
if (!cctx) {
cctx = ZSTD_createCCtx();
FUZZ_ASSERT(cctx);
}
if (!dctx) {
dctx = ZSTD_createDCtx();
FUZZ_ASSERT(dctx);
}
size_t const result = roundTripTest(rBuf, rBufSize,
cBuf, cBufSize,
generatedSrcSize,
dictBuffer, dictSize,
nbSequences,
wLog, cLevel, hasDict);
FUZZ_ZASSERT(result);
FUZZ_ASSERT_MSG(result == generatedSrcSize, "Incorrect regenerated size");
FUZZ_ASSERT_MSG(!FUZZ_memcmp(generatedSrc, rBuf, generatedSrcSize), "Corruption!");
free(rBuf);
free(cBuf);
FUZZ_dataProducer_free(producer);
if (hasDict) {
free(dictBuffer);
}
#ifndef STATEFUL_FUZZING
ZSTD_freeCCtx(cctx); cctx = NULL;
ZSTD_freeDCtx(dctx); dctx = NULL;
free(generatedSequences); generatedSequences = NULL;
free(generatedSrc); generatedSrc = NULL;
free(literalsBuffer); literalsBuffer = NULL;
#endif
return 0;
}