// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <algorithm>
#include <memory>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <fuzzer/FuzzedDataProvider.h>
#include "zlib.h"
// Fuzzer builds often have NDEBUG set, so roll our own assert macro.
#define ASSERT(cond) \
do { \
if (!(cond)) { \
fprintf(stderr, "%s:%d Assert failed: %s\n", __FILE__, __LINE__, #cond); \
exit(1); \
} \
} while (0)
static void chunked_inflate(gz_header* header,
uint8_t* data,
size_t size,
size_t in_chunk_size,
size_t out_chunk_size) {
z_stream stream;
stream.next_in = data;
stream.avail_in = 0;
stream.zalloc = Z_NULL;
stream.zfree = Z_NULL;
static const int kDefaultWindowBits = MAX_WBITS;
static const int kGzipOrZlibHeader = 32;
ASSERT(inflateInit2(&stream, kDefaultWindowBits + kGzipOrZlibHeader) == Z_OK);
ASSERT(inflateGetHeader(&stream, header) == Z_OK);
auto out_buffer = std::make_unique<uint8_t[]>(out_chunk_size);
while (true) {
stream.next_in = &data[stream.total_in];
stream.avail_in =
std::min(in_chunk_size, size - static_cast<size_t>(stream.total_in));
stream.next_out = out_buffer.get();
stream.avail_out = out_chunk_size;
if (inflate(&stream, stream.avail_in == 0 ? Z_SYNC_FLUSH : Z_NO_FLUSH) !=
Z_OK) {
break;
}
}
inflateEnd(&stream);
}
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
if (size > 250 * 1024) {
// Cap the input size so the fuzzer doesn't time out. For example,
// crbug.com/1362206 saw timeouts with 450 KB input, so use a limit that's
// well below that but still large enough to hit most code.
return 0;
}
FuzzedDataProvider fdp(data, size);
// Fuzz zlib's inflate() with inflateGetHeader() enabled, various sizes for
// the gz_header field sizes, and various-sized chunks for input/output. This
// would have found CVE-2022-37434 which was a heap buffer read overflow when
// filling in gz_header's extra field.
gz_header header;
header.extra_max = fdp.ConsumeIntegralInRange(0, 100000);
header.name_max = fdp.ConsumeIntegralInRange(0, 100000);
header.comm_max = fdp.ConsumeIntegralInRange(0, 100000);
auto extra_buf = std::make_unique<uint8_t[]>(header.extra_max);
auto name_buf = std::make_unique<uint8_t[]>(header.name_max);
auto comment_buf = std::make_unique<uint8_t[]>(header.comm_max);
header.extra = extra_buf.get();
header.name = name_buf.get();
header.comment = comment_buf.get();
size_t in_chunk_size = fdp.ConsumeIntegralInRange(1, 4097);
size_t out_chunk_size = fdp.ConsumeIntegralInRange(1, 4097);
std::vector<uint8_t> remaining_data = fdp.ConsumeRemainingBytes<uint8_t>();
chunked_inflate(&header, remaining_data.data(), remaining_data.size(),
in_chunk_size, out_chunk_size);
return 0;
}
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