Add a fuzzer for png_process_data

testing/libfuzzer/fuzzers/libpng_read_fuzzer.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // 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 "base/bind.h"
 #include "base/callback_helpers.h"
 #define PNG_INTERNAL
 #include "third_party/libpng/png.h"
 
+#ifndef PNG_FUZZ_PROGRESSIVE
+
+// Read sequentially, with png_read_row.
 struct BufState {
   const uint8_t* data;
   size_t bytes_left;
 };
 
 void user_read_data(png_structp png_ptr, png_bytep data, png_size_t length) {
   BufState* buf_state = static_cast<BufState*>(png_get_io_ptr(png_ptr));
   if (length > buf_state->bytes_left) {
     png_error(png_ptr, "read error");
   }
   memcpy(data, buf_state->data, length);
   buf_state->bytes_left -= length;
   buf_state->data += length;
 }
+
+#endif  // PNG_FUZZ_PROGRESSIVE
+
 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;
   }
 
@@ skipping 14 matching lines @@
 #endif
 
   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);
 
   base::ScopedClosureRunner struct_deleter(base::Bind(
         &png_destroy_read_struct, &png_ptr, &info_ptr, nullptr));
 
+#ifdef PNG_FUZZ_PROGRESSIVE
+  png_set_progressive_read_fn(png_ptr, nullptr, nullptr, nullptr, nullptr);
+  png_process_data(png_ptr, info_ptr, const_cast<uint8_t*>(data), size);
+#else
   // Setting up reading from buffer.
   std::unique_ptr<BufState> buf_state(new BufState());
   buf_state->data = data + kPngHeaderSize;
   buf_state->bytes_left = size - kPngHeaderSize;
   png_set_read_fn(png_ptr, buf_state.get(), user_read_data);
   png_set_sig_bytes(png_ptr, kPngHeaderSize);
 
   // libpng error handling.
   if (setjmp(png_jmpbuf(png_ptr))) {
     return 0;
@@ skipping 25 matching lines @@
     return 0;
 
   int passes = png_set_interlace_handling(png_ptr);
   png_start_read_image(png_ptr);
 
   for (int pass = 0; pass < passes; ++pass) {
     for (png_uint_32 y = 0; y < height; ++y) {
       png_read_row(png_ptr, static_cast<png_bytep>(row), NULL);
     }
   }
+#endif  // PNG_FUZZ_PROGRESSIVE
 
   return 0;
 }