blob: 01eb1e1d51f9cfc5d03918c619a23be004ff0fa7 [file] [log] [blame]
// Copyright 2017 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include <stdint.h>
#include <vector>
#include "core/fxcodec/gif/lzw_decompressor.h"
#include "core/fxcrt/compiler_specific.h"
#include "core/fxcrt/fx_safe_types.h"
#include "core/fxcrt/numerics/safe_conversions.h"
#include "core/fxcrt/span.h"
// Between 2x and 5x is a standard range for LZW according to a quick
// search of papers. Running up to 10x to catch any niche cases.
constexpr uint32_t kMinCompressionRatio = 2;
constexpr uint32_t kMaxCompressionRatio = 10;
static constexpr size_t kMaxFuzzBytes = 1024 * 1024 * 1024; // 1 GB.
void LZWFuzz(pdfium::span<const uint8_t> src_buf,
uint8_t color_exp,
uint8_t code_exp) {
std::unique_ptr<LZWDecompressor> decompressor =
LZWDecompressor::Create(color_exp, code_exp);
if (!decompressor)
return;
for (uint32_t compressions_ratio = kMinCompressionRatio;
compressions_ratio <= kMaxCompressionRatio; compressions_ratio++) {
FX_SAFE_UINT32 safe_dest_size = src_buf.size();
safe_dest_size *= compressions_ratio;
uint32_t dest_size = safe_dest_size.ValueOrDie();
std::vector<uint8_t> dest_buf(dest_size);
decompressor->SetSource(src_buf);
if (LZWDecompressor::Status::kInsufficientDestSize !=
decompressor->Decode(dest_buf.data(), &dest_size)) {
return;
}
}
}
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
// SAFETY: required from fuzzer
auto data_span = UNSAFE_BUFFERS(pdfium::make_span(data, size));
// Need at least 3 bytes to do anything.
if (data_span.size() < 3 || data_span.size() > kMaxFuzzBytes) {
return 0;
}
// Normally the GIF would provide the code and color sizes, instead, going
// to assume they are the first two bytes of data provided.
uint8_t color_exp = data_span[0];
uint8_t code_exp = data_span[1];
pdfium::span<const uint8_t> lzw_data = data_span.subspan(2);
// Check that there isn't going to be an overflow in the destination buffer
// size.
if (lzw_data.size() >
std::numeric_limits<uint32_t>::max() / kMaxCompressionRatio) {
return 0;
}
LZWFuzz(lzw_data, color_exp, code_exp);
return 0;
}