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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <vector>
#include "third_party/abseil-cpp/absl/cleanup/cleanup.h"
#define PNG_INTERNAL
#include "third_party/libpng/png.h"
void* limited_malloc(png_structp, png_alloc_size_t size) {
// libpng may allocate large amounts of memory that the fuzzer reports as
// an error. In order to silence these errors, make libpng fail when trying
// to allocate a large amount.
// This number is chosen to match the default png_user_chunk_malloc_max.
if (size > 8000000)
return nullptr;
return malloc(size);
}
void default_free(png_structp, png_voidp ptr) {
return free(ptr);
}
static const int kPngHeaderSize = 8;
// Entry point for LibFuzzer.
// Roughly follows the libpng book example:
// http://www.libpng.org/pub/png/book/chapter13.html
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
if (size < kPngHeaderSize) {
return 0;
}
std::vector<unsigned char> v(data, data + size);
if (png_sig_cmp(v.data(), 0, kPngHeaderSize)) {
// not a PNG.
return 0;
}
png_structp png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
assert(png_ptr);
#ifdef MEMORY_SANITIZER
// To avoid OOM with MSan (crbug.com/648073). These values are recommended as
// safe settings by https://github.com/glennrp/libpng/blob/libpng16/pngusr.dfa
png_set_user_limits(png_ptr, 65535, 65535);
#endif
// Not all potential OOM are due to images with large widths and heights.
// Use a custom allocator that fails for large allocations.
png_set_mem_fn(png_ptr, nullptr, limited_malloc, default_free);
png_set_crc_action(png_ptr, PNG_CRC_QUIET_USE, PNG_CRC_QUIET_USE);
png_infop info_ptr = png_create_info_struct(png_ptr);
assert(info_ptr);
absl::Cleanup struct_deleter = [&png_ptr, &info_ptr] {
png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
};
if (setjmp(png_jmpbuf(png_ptr))) {
return 0;
}
png_set_progressive_read_fn(png_ptr, nullptr, nullptr, nullptr, nullptr);
png_process_data(png_ptr, info_ptr, const_cast<uint8_t*>(data), size);
return 0;
}
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