[libpng16] Added contrib/oss-fuzz directory

ANNOUNCE

-Libpng 1.6.32rc01 - August 18, 2017
+Libpng 1.6.32rc01 - August 22, 2017
 
 This is not intended to be a public release. It will be replaced
 within a few weeks by a public version or by another test version.
@@ -104,6 +104,10 @@ Version 1.6.32rc01 [August 18, 2017]
     names differ only in case; this causes problems with some platforms
     (github issue #172).
 
+Version 1.6.32rc02 [August 22, 2017]
+  Added contrib/oss-fuzz directory which contains a target for the oss-fuzz
+    project.
+
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement

CHANGES

@@ -5987,6 +5987,10 @@ Version 1.6.32rc01 [August 18, 2017]
     names differ only in case; this causes problems with some platforms
     (github issue #172).
 
+Version 1.6.32rc02 [August 22, 2017]
+  Added contrib/oss-fuzz directory which contains a target for the oss-fuzz
+    project.
+
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement

contrib/oss-fuzz/README.txt

+Files in this directory are used by the oss-fuzz target for "fuzzing libpng.
+They were originally licensed by google inc, using the Apache-2.0 license,
+which may be found at https://www.apache.org/licenses/LICENSE-2.0.

contrib/oss-fuzz/libpng_read_fuzzer.cc

+
+// libpng_read_fuzzer.cc
+// Copyright 2017 Glenn Randers-Pehrson
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that could
+// previously be found in a LICENSE file.
+
+// The modifications by Glenn Randers-Pehrson include the addition of a
+// PNG_CLEANUP macro and setting the option to ignore ADLER32 checksums.
+
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <vector>
+
+#define PNG_INTERNAL
+#include "png.h"
+
+#define PNG_CLEANUP \
+    if(png_handler.png_ptr) \
+    { \
+      if (png_handler.info_ptr) \
+        png_destroy_read_struct(&png_handler.png_ptr, &png_handler.info_ptr,\
+          nullptr); \
+      else \
+        png_destroy_read_struct(&png_handler.png_ptr, nullptr, nullptr); \
+     }
+
+struct BufState {
+  const uint8_t* data;
+  size_t bytes_left;
+};
+
+struct PngObjectHandler {
+  png_infop info_ptr = nullptr;
+  png_structp png_ptr = nullptr;
+  png_voidp row_ptr = nullptr;
+  BufState* buf_state = nullptr;
+
+  ~PngObjectHandler() {
+    if (row_ptr && png_ptr) {
+      png_free(png_ptr, row_ptr);
+    }
+    if (png_ptr && info_ptr) {
+      png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
+    }
+    delete buf_state;
+  }
+};
+
+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;
+}
+
+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;
+  }
+
+  PngObjectHandler png_handler;
+  png_handler.png_ptr = png_create_read_struct
+    (PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
+  if (!png_handler.png_ptr) {
+    return 0;
+  }
+
+  png_handler.info_ptr = png_create_info_struct(png_handler.png_ptr);
+  if (!png_handler.info_ptr) {
+    PNG_CLEANUP
+    return 0;
+  }
+
+  png_set_crc_action(png_handler.png_ptr, PNG_CRC_QUIET_USE, PNG_CRC_QUIET_USE);
+#ifdef PNG_IGNORE_ADLER32
+  png_set_option(read_ptr, PNG_IGNORE_ADLER32, PNG_OPTION_ON);
+#endif
+
+  // Setting up reading from buffer.
+  png_handler.buf_state = new BufState();
+  png_handler.buf_state->data = data + kPngHeaderSize;
+  png_handler.buf_state->bytes_left = size - kPngHeaderSize;
+  png_set_read_fn(png_handler.png_ptr, png_handler.buf_state, user_read_data);
+  png_set_sig_bytes(png_handler.png_ptr, kPngHeaderSize);
+
+  if (setjmp(png_jmpbuf(png_handler.png_ptr))) {
+    PNG_CLEANUP
+    return 0;
+  }
+
+  // Reading.
+  png_read_info(png_handler.png_ptr, png_handler.info_ptr);
+  png_handler.row_ptr = png_malloc(
+      png_handler.png_ptr, png_get_rowbytes(png_handler.png_ptr,
+                                               png_handler.info_ptr));
+
+  // reset error handler to put png_deleter into scope.
+  if (setjmp(png_jmpbuf(png_handler.png_ptr))) {
+    PNG_CLEANUP
+    return 0;
+  }
+
+  png_uint_32 width, height;
+  int bit_depth, color_type, interlace_type, compression_type;
+  int filter_type;
+
+  if (!png_get_IHDR(png_handler.png_ptr, png_handler.info_ptr, &width,
+                    &height, &bit_depth, &color_type, &interlace_type,
+                    &compression_type, &filter_type)) {
+    PNG_CLEANUP
+    return 0;
+  }
+
+  // This is going to be too slow.
+  if (width && height > 100000000 / width) {
+    PNG_CLEANUP
+    return 0;
+  }
+
+  int passes = png_set_interlace_handling(png_handler.png_ptr);
+  png_start_read_image(png_handler.png_ptr);
+
+  for (int pass = 0; pass < passes; ++pass) {
+    for (png_uint_32 y = 0; y < height; ++y) {
+      png_read_row(png_handler.png_ptr,
+                   static_cast<png_bytep>(png_handler.row_ptr), nullptr);
+    }
+  }
+
+  PNG_CLEANUP
+  return 0;
+}