65 lines
2.1 KiB
C++
65 lines
2.1 KiB
C++
// Copyright 2017 The PDFium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include <stddef.h>
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#include <stdint.h>
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#include <vector>
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#include "core/fxcodec/gif/lzw_decompressor.h"
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#include "third_party/base/numerics/safe_conversions.h"
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// Between 2x and 5x is a standard range for LZW according to a quick
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// search of papers. Running up to 10x to catch any niche cases.
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constexpr uint32_t kMinCompressionRatio = 2;
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constexpr uint32_t kMaxCompressionRatio = 10;
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static constexpr size_t kMaxFuzzBytes = 1024 * 1024 * 1024; // 1 GB.
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void LZWFuzz(const uint8_t* src_buf,
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uint32_t src_size,
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uint8_t color_exp,
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uint8_t code_exp) {
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std::unique_ptr<LZWDecompressor> decompressor =
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LZWDecompressor::Create(color_exp, code_exp);
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if (!decompressor)
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return;
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for (uint32_t compressions_ratio = kMinCompressionRatio;
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compressions_ratio <= kMaxCompressionRatio; compressions_ratio++) {
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std::vector<uint8_t> dest_buf(compressions_ratio * src_size);
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// This cast should be safe since the caller is checking for overflow on
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// the initial data.
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uint32_t dest_size = static_cast<uint32_t>(dest_buf.size());
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decompressor->SetSource(src_buf, src_size);
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if (LZWDecompressor::Status::kInsufficientDestSize !=
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decompressor->Decode(dest_buf.data(), &dest_size)) {
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return;
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}
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}
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}
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
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// Need at least 3 bytes to do anything.
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if (size < 3 || size > kMaxFuzzBytes)
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return 0;
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// Normally the GIF would provide the code and color sizes, instead, going
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// to assume they are the first two bytes of data provided.
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uint8_t color_exp = data[0];
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uint8_t code_exp = data[1];
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const uint8_t* lzw_data = data + 2;
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uint32_t lzw_data_size = static_cast<uint32_t>(size - 2);
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// Check that there isn't going to be an overflow in the destination buffer
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// size.
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if (lzw_data_size >
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std::numeric_limits<uint32_t>::max() / kMaxCompressionRatio) {
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return 0;
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}
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LZWFuzz(lzw_data, lzw_data_size, color_exp, code_exp);
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return 0;
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}
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