Apply some sanity checks to the values coming back to us from FFmpeg.

Put the limits in a new standalone header file that can be re-used in other
place where we have similar limits.

BUG=NONE
TEST=media_unittests pass

Review URL: http://codereview.chromium.org/200011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@25416 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 42 insertions, 1 deletions

diff --git a/media/base/limits.h b/media/base/limits.h
new file mode 100644
index 0000000..583d6dd
--- /dev/null
+++ b/media/base/limits.h
@@ -0,0 +1,28 @@
+// Copyright (c) 2009 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.
+
+// Contains limit definition constants for the media subsystem.
+
+#ifndef MEDIA_BASE_LIMITS_H_
+#define MEDIA_BASE_LIMITS_H_
+
+#include "base/basictypes.h"
+
+namespace media {
+
+struct Limits {
+  // For video.
+  static const size_t kMaxDimension = (1 << 15) - 1;  // 32767
+  static const size_t kMaxCanvas = (1 << (14 * 2));  // 16384 x 16384
+
+  // For audio.
+  static const size_t kMaxSampleRate = 192000;
+  static const size_t kMaxChannels = 32;
+  static const size_t kMaxBPS = 64;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_LIMITS_H_
+
diff --git a/media/filters/ffmpeg_audio_decoder.cc b/media/filters/ffmpeg_audio_decoder.cc
index 07c09ac..8a7991a 100644
--- a/media/filters/ffmpeg_audio_decoder.cc
+++ b/media/filters/ffmpeg_audio_decoder.cc
@@ -5,6 +5,7 @@
 #include "media/filters/ffmpeg_audio_decoder.h"
 
 #include "media/base/data_buffer.h"
+#include "media/base/limits.h"
 #include "media/filters/ffmpeg_common.h"
 #include "media/filters/ffmpeg_demuxer.h"
 
@@ -38,9 +39,17 @@ bool FFmpegAudioDecoder::OnInitialize(DemuxerStream* demuxer_stream) {
 
   // Grab the AVStream's codec context and make sure we have sensible values.
   codec_context_ = av_stream->codec;
+  int bps = av_get_bits_per_sample_format(codec_context_->sample_fmt);
   DCHECK_GT(codec_context_->channels, 0);
-  DCHECK_GT(av_get_bits_per_sample_format(codec_context_->sample_fmt), 0);
+  DCHECK_GT(bps, 0);
   DCHECK_GT(codec_context_->sample_rate, 0);
+  if (codec_context_->channels == 0 ||
+      static_cast<size_t>(codec_context_->channels) > Limits::kMaxChannels ||
+      bps == 0 ||
+      static_cast<size_t>(bps) > Limits::kMaxBPS ||
+      codec_context_->sample_rate == 0 ||
+      static_cast<size_t>(codec_context_->sample_rate) > Limits::kMaxSampleRate)
+      return false;
 
   // Serialize calls to avcodec_open().
   AVCodec* codec = avcodec_find_decoder(codec_context_->codec_id);
diff --git a/media/filters/ffmpeg_video_decoder.cc b/media/filters/ffmpeg_video_decoder.cc
index 8d54c8b..bd3ed981 100644
--- a/media/filters/ffmpeg_video_decoder.cc
+++ b/media/filters/ffmpeg_video_decoder.cc
@@ -2,6 +2,7 @@
 // source code is governed by a BSD-style license that can be found in the
 // LICENSE file.
 
+#include "media/base/limits.h"
 #include "media/base/video_frame_impl.h"
 #include "media/filters/ffmpeg_common.h"
 #include "media/filters/ffmpeg_demuxer.h"
@@ -65,6 +66,9 @@ bool FFmpegVideoDecoder::OnInitialize(DemuxerStream* demuxer_stream) {
   width_ = av_stream->codec->width;
   height_ = av_stream->codec->height;
   *time_base_ = av_stream->time_base;
+  if (width_ > Limits::kMaxDimension || height_ > Limits::kMaxDimension ||
+      width_ * height_ > Limits::kMaxCanvas)
+      return false;
 
   media_format_.SetAsString(MediaFormat::kMimeType,
                             mime_type::kUncompressedVideo);