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Merge pull request #752 from terrelln/fuzzers

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[ossfuzz] Improve the fuzzers
This commit is contained in:
Yann Collet 2019-07-16 11:18:09 -07:00 committed by GitHub
commit 7654a5a6d2
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GPG Key ID: 4AEE18F83AFDEB23
9 changed files with 314 additions and 52 deletions
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49
lib/lz4.c
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@ -1647,7 +1647,11 @@ LZ4_decompress_generic(
/* Special cases */
assert(lowPrefix <= op);
if ((endOnInput) && (unlikely(outputSize==0))) { return ((srcSize==1) && (*ip==0)) ? 0 : -1; } /* Empty output buffer */
if ((endOnInput) && (unlikely(outputSize==0))) {
/* Empty output buffer */
if (partialDecoding) return 0;
return ((srcSize==1) && (*ip==0)) ? 0 : -1;
}
if ((!endOnInput) && (unlikely(outputSize==0))) { return (*ip==0 ? 1 : -1); }
if ((endOnInput) && unlikely(srcSize==0)) { return -1; }
@ -1855,21 +1859,50 @@ LZ4_decompress_generic(
if ( ((endOnInput) && ((cpy>oend-MFLIMIT) || (ip+length>iend-(2+1+LASTLITERALS))) )
|| ((!endOnInput) && (cpy>oend-WILDCOPYLENGTH)) )
{
/* We've either hit the input parsing restriction or the output parsing restriction.
* If we've hit the input parsing condition then this must be the last sequence.
* If we've hit the output parsing condition then we are either using partialDecoding
* or we've hit the output parsing condition.
*/
if (partialDecoding) {
if (cpy > oend) { cpy = oend; assert(op<=oend); length = (size_t)(oend-op); } /* Partial decoding : stop in the middle of literal segment */
if ((endOnInput) && (ip+length > iend)) { goto _output_error; } /* Error : read attempt beyond end of input buffer */
/* Since we are partial decoding we may be in this block because of the output parsing
* restriction, which is not valid since the output buffer is allowed to be undersized.
*/
assert(endOnInput);
/* If we're in this block because of the input parsing condition, then we must be on the
* last sequence (or invalid), so we must check that we exactly consume the input.
*/
if ((ip+length>iend-(2+1+LASTLITERALS)) && (ip+length != iend)) { goto _output_error; }
assert(ip+length <= iend);
/* We are finishing in the middle of a literals segment.
* Break after the copy.
*/
if (cpy > oend) {
cpy = oend;
assert(op<=oend);
length = (size_t)(oend-op);
}
assert(ip+length <= iend);
} else {
if ((!endOnInput) && (cpy != oend)) { goto _output_error; } /* Error : block decoding must stop exactly there */
if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) { goto _output_error; } /* Error : input must be consumed */
/* We must be on the last sequence because of the parsing limitations so check
* that we exactly regenerate the original size (must be exact when !endOnInput).
*/
if ((!endOnInput) && (cpy != oend)) { goto _output_error; }
/* We must be on the last sequence (or invalid) because of the parsing limitations
* so check that we exactly consume the input and don't overrun the output buffer.
*/
if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) { goto _output_error; }
}
memmove(op, ip, length); /* supports overlapping memory regions, which only matters for in-place decompression scenarios */
ip += length;
op += length;
if (!partialDecoding || (cpy == oend)) {
/* Necessarily EOF, due to parsing restrictions */
/* Necessarily EOF when !partialDecoding. When partialDecoding
* it is EOF if we've either filled the output buffer or hit
* the input parsing restriction.
*/
if (!partialDecoding || (cpy == oend) || (ip == iend)) {
break;
}
} else {
LZ4_wildCopy8(op, ip, cpy); /* may overwrite up to WILDCOPYLENGTH beyond cpy */
ip += length; op = cpy;

1
ossfuzz/Makefile
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@ -57,3 +57,4 @@ $(LZ4DIR)/liblz4.a:
.PHONY: clean
clean: compress_fuzzer_clean decompress_fuzzer_clean
$(MAKE) -C $(LZ4DIR) clean

52
ossfuzz/compress_fuzzer.c
View File

@ -1,25 +1,51 @@
/**
* This fuzz target attempts to compress the fuzzed data with the simple
* compression function with an output buffer that may be too small to
* ensure that the compressor never crashes.
*/
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include "lz4.h"
#include <string.h>
#define CHECK(COND) if (!(COND)) { abort(); }
#include "fuzz_helpers.h"
#include "lz4.h"
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
size_t const compressed_dest_size = LZ4_compressBound(size);
char *const dest_buffer = (char *)malloc(compressed_dest_size);
uint32_t seed = FUZZ_seed(&data, &size);
size_t const dstCapacity = FUZZ_rand32(&seed, 0, LZ4_compressBound(size));
char* const dst = (char*)malloc(dstCapacity);
char* const rt = (char*)malloc(size);
CHECK(dest_buffer != NULL);
FUZZ_ASSERT(dst);
FUZZ_ASSERT(rt);
// Allocation succeeded, try compressing the incoming data.
int result = LZ4_compress_default((const char*)data,
dest_buffer,
size,
compressed_dest_size);
CHECK(result != 0);
/* If compression succeeds it must round trip correctly. */
{
int const dstSize = LZ4_compress_default((const char*)data, dst,
size, dstCapacity);
if (dstSize > 0) {
int const rtSize = LZ4_decompress_safe(dst, rt, dstSize, size);
FUZZ_ASSERT_MSG(rtSize == size, "Incorrect regenerated size");
FUZZ_ASSERT_MSG(!memcmp(data, rt, size), "Corruption!");
}
}
free(dest_buffer);
if (dstCapacity > 0) {
/* Compression succeeds and must round trip correctly. */
int compressedSize = size;
int const dstSize = LZ4_compress_destSize((const char*)data, dst,
&compressedSize, dstCapacity);
FUZZ_ASSERT(dstSize > 0);
int const rtSize = LZ4_decompress_safe(dst, rt, dstSize, size);
FUZZ_ASSERT_MSG(rtSize == compressedSize, "Incorrect regenerated size");
FUZZ_ASSERT_MSG(!memcmp(data, rt, compressedSize), "Corruption!");
}
return 0;
free(dst);
free(rt);
return 0;
}

60
ossfuzz/decompress_fuzzer.c
View File

@ -1,28 +1,58 @@
/**
* This fuzz target attempts to decompress the fuzzed data with the simple
* decompression function to ensure the decompressor never crashes.
*/
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include "lz4.h"
#include <string.h>
#define CHECK(COND) if (!(COND)) { abort(); }
#include "fuzz_helpers.h"
#include "lz4.h"
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
// TODO: Size input buffer pseudo-randomly based on seed extracted from input
size_t const buffer_size = 10 * 1024 * 1024;
char *const dest_buffer = (char *)malloc(buffer_size);
CHECK(dest_buffer != NULL);
uint32_t seed = FUZZ_seed(&data, &size);
size_t const dstCapacity = FUZZ_rand32(&seed, 0, 4 * size);
size_t const smallDictSize = size + 1;
size_t const largeDictSize = 64 * 1024 - 1;
size_t const dictSize = MAX(smallDictSize, largeDictSize);
char* const dst = (char*)malloc(dstCapacity);
char* const dict = (char*)malloc(dictSize + size);
char* const largeDict = dict;
char* const dataAfterDict = dict + dictSize;
char* const smallDict = dataAfterDict - smallDictSize;
// Allocation succeeded, try decompressing the incoming data.
int result = LZ4_decompress_safe((const char*)data,
dest_buffer,
size,
buffer_size);
FUZZ_ASSERT(dst);
FUZZ_ASSERT(dict);
// Ignore the result of decompression.
(void)result;
/* Prepare the dictionary. The data doesn't matter for decompression. */
memset(dict, 0, dictSize);
memcpy(dataAfterDict, data, size);
free(dest_buffer);
/* Decompress using each possible dictionary configuration. */
/* No dictionary. */
LZ4_decompress_safe_usingDict((char const*)data, dst, size,
dstCapacity, NULL, 0);
/* Small external dictonary. */
LZ4_decompress_safe_usingDict((char const*)data, dst, size,
dstCapacity, smallDict, smallDictSize);
/* Large external dictionary. */
LZ4_decompress_safe_usingDict((char const*)data, dst, size,
dstCapacity, largeDict, largeDictSize);
/* Small prefix. */
LZ4_decompress_safe_usingDict((char const*)dataAfterDict, dst, size,
dstCapacity, smallDict, smallDictSize);
/* Large prefix. */
LZ4_decompress_safe_usingDict((char const*)data, dst, size,
dstCapacity, largeDict, largeDictSize);
/* Partial decompression. */
LZ4_decompress_safe_partial((char const*)data, dst, size,
dstCapacity, dstCapacity);
free(dst);
free(dict);
return 0;
return 0;
}

48
ossfuzz/fuzz.h Normal file
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@ -0,0 +1,48 @@
/**
* Fuzz target interface.
* Fuzz targets have some common parameters passed as macros during compilation.
* Check the documentation for each individual fuzzer for more parameters.
*
* @param FUZZ_RNG_SEED_SIZE:
* The number of bytes of the source to look at when constructing a seed
* for the deterministic RNG. These bytes are discarded before passing
* the data to lz4 functions. Every fuzzer initializes the RNG exactly
* once before doing anything else, even if it is unused.
* Default: 4.
* @param LZ4_DEBUG:
* This is a parameter for the lz4 library. Defining `LZ4_DEBUG=1`
* enables assert() statements in the lz4 library. Higher levels enable
* logging, so aren't recommended. Defining `LZ4_DEBUG=1` is
* recommended.
* @param LZ4_FORCE_MEMORY_ACCESS:
* This flag controls how the zstd library accesses unaligned memory.
* It can be undefined, or 0 through 2. If it is undefined, it selects
* the method to use based on the compiler. If testing with UBSAN set
* MEM_FORCE_MEMORY_ACCESS=0 to use the standard compliant method.
* @param FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
* This is the canonical flag to enable deterministic builds for fuzzing.
* Changes to zstd for fuzzing are gated behind this define.
* It is recommended to define this when building zstd for fuzzing.
*/
#ifndef FUZZ_H
#define FUZZ_H
#ifndef FUZZ_RNG_SEED_SIZE
# define FUZZ_RNG_SEED_SIZE 4
#endif
#include <stddef.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size);
#ifdef __cplusplus
}
#endif
#endif

89
ossfuzz/fuzz_helpers.h Normal file
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@ -0,0 +1,89 @@
/*
* Copyright (c) 2016-present, 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).
*/
/**
* Helper functions for fuzzing.
*/
#ifndef FUZZ_HELPERS_H
#define FUZZ_HELPERS_H
#include "fuzz.h"
#include "xxhash.h"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef __cplusplus
extern "C" {
#endif
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define FUZZ_QUOTE_IMPL(str) #str
#define FUZZ_QUOTE(str) FUZZ_QUOTE_IMPL(str)
/**
* Asserts for fuzzing that are always enabled.
*/
#define FUZZ_ASSERT_MSG(cond, msg) \
((cond) ? (void)0 \
: (fprintf(stderr, "%s: %u: Assertion: `%s' failed. %s\n", __FILE__, \
__LINE__, FUZZ_QUOTE(cond), (msg)), \
abort()))
#define FUZZ_ASSERT(cond) FUZZ_ASSERT_MSG((cond), "");
#if defined(__GNUC__)
#define FUZZ_STATIC static __inline __attribute__((unused))
#elif defined(__cplusplus) || \
(defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
#define FUZZ_STATIC static inline
#elif defined(_MSC_VER)
#define FUZZ_STATIC static __inline
#else
#define FUZZ_STATIC static
#endif
/**
* Deterministically constructs a seed based on the fuzz input.
* Consumes up to the first FUZZ_RNG_SEED_SIZE bytes of the input.
*/
FUZZ_STATIC uint32_t FUZZ_seed(uint8_t const **src, size_t* size) {
uint8_t const *data = *src;
size_t const toHash = MIN(FUZZ_RNG_SEED_SIZE, *size);
*size -= toHash;
*src += toHash;
return XXH32(data, toHash, 0);
}
#define FUZZ_rotl32(x, r) (((x) << (r)) | ((x) >> (32 - (r))))
FUZZ_STATIC uint32_t FUZZ_rand(uint32_t *state) {
static const uint32_t prime1 = 2654435761U;
static const uint32_t prime2 = 2246822519U;
uint32_t rand32 = *state;
rand32 *= prime1;
rand32 += prime2;
rand32 = FUZZ_rotl32(rand32, 13);
*state = rand32;
return rand32 >> 5;
}
/* Returns a random numer in the range [min, max]. */
FUZZ_STATIC uint32_t FUZZ_rand32(uint32_t *state, uint32_t min, uint32_t max) {
uint32_t random = FUZZ_rand(state);
return min + (random % (max - min + 1));
}
#ifdef __cplusplus
}
#endif
#endif

50
ossfuzz/round_trip_fuzzer.c Normal file
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@ -0,0 +1,50 @@
/**
* This fuzz target performs a lz4 round-trip test (compress & decompress),
* compares the result with the original, and calls abort() on corruption.
*/
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "fuzz_helpers.h"
#include "lz4.h"
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
uint32_t seed = FUZZ_seed(&data, &size);
size_t const dstCapacity = LZ4_compressBound(size);
char* const dst = (char*)malloc(dstCapacity);
char* const rt = (char*)malloc(size);
FUZZ_ASSERT(dst);
FUZZ_ASSERT(rt);
/* Compression must succeed and round trip correctly. */
int const dstSize = LZ4_compress_default((const char*)data, dst,
size, dstCapacity);
FUZZ_ASSERT(dstSize > 0);
int const rtSize = LZ4_decompress_safe(dst, rt, dstSize, size);
FUZZ_ASSERT_MSG(rtSize == size, "Incorrect size");
FUZZ_ASSERT_MSG(!memcmp(data, rt, size), "Corruption!");
/* Partial decompression must succeed. */
{
size_t const partialCapacity = FUZZ_rand32(&seed, 0, size);
char* const partial = (char*)malloc(partialCapacity);
FUZZ_ASSERT(partial);
int const partialSize = LZ4_decompress_safe_partial(
dst, partial, dstSize, partialCapacity, partialCapacity);
FUZZ_ASSERT(partialSize >= 0);
FUZZ_ASSERT_MSG(partialSize == partialCapacity, "Incorrect size");
FUZZ_ASSERT_MSG(!memcmp(data, partial, partialSize), "Corruption!");
free(partial);
}
free(dst);
free(rt);
return 0;
}

2
ossfuzz/standaloneengine.c
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@ -2,7 +2,7 @@
#include <stdio.h>
#include <stdlib.h>
#include "testinput.h"
#include "fuzz.h"
/**
* Main procedure for standalone fuzzing engine.

15
ossfuzz/testinput.h
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@ -1,15 +0,0 @@
#ifndef TESTINPUT_H_INCLUDED
#define TESTINPUT_H_INCLUDED
#include <inttypes.h>
#if defined (__cplusplus)
extern "C" {
#endif
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
#if defined(__cplusplus)
}
#endif
#endif