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Fix potential unsafe access to VCMTimestampMap::data

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The access to |_timestampMap| was guarded by a lock but
not the access to the data pointer stored in |_timestampMap|.
There was a potential race condition if new data was added
in VCMGenericDecoder::Decode() while the data pointer
retrieved from _timestampMap.Pop() was being used in
VCMDecodedFrameCallback::Decoded().

This CL moves the storage of data to within |_timestampMap|,
instead of being a pointer so that it's guarded by the same
lock.

Bug: webrtc:11229
Change-Id: I3f2afb568ed724db5719d508a73de402c4531dec
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/209361
Commit-Queue: Johannes Kron <kron@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33374}
This commit is contained in:
Johannes Kron
2021-03-03 14:39:44 +01:00
committed by Commit Bot
parent 752cbaba90
commit b6b782da68
5 changed files with 44 additions and 41 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
modules/video_coding/generic_decoder.cc
View File

@ -91,7 +91,7 @@ void VCMDecodedFrameCallback::Decoded(VideoFrame& decodedImage,
"timestamp", decodedImage.timestamp());
// TODO(holmer): We should improve this so that we can handle multiple
// callbacks from one call to Decode().
VCMFrameInformation* frameInfo;
absl::optional<VCMFrameInformation> frameInfo;
int timestamp_map_size = 0;
{
MutexLock lock(&lock_);
@ -99,7 +99,7 @@ void VCMDecodedFrameCallback::Decoded(VideoFrame& decodedImage,
timestamp_map_size = _timestampMap.Size();
}
if (frameInfo == NULL) {
if (!frameInfo) {
RTC_LOG(LS_WARNING) << "Too many frames backed up in the decoder, dropping "
"this one.";
_receiveCallback->OnDroppedFrames(1);
@ -196,14 +196,14 @@ void VCMDecodedFrameCallback::OnDecoderImplementationName(
}
void VCMDecodedFrameCallback::Map(uint32_t timestamp,
VCMFrameInformation* frameInfo) {
const VCMFrameInformation& frameInfo) {
MutexLock lock(&lock_);
_timestampMap.Add(timestamp, frameInfo);
}
int32_t VCMDecodedFrameCallback::Pop(uint32_t timestamp) {
MutexLock lock(&lock_);
if (_timestampMap.Pop(timestamp) == NULL) {
if (_timestampMap.Pop(timestamp) == absl::nullopt) {
return VCM_GENERAL_ERROR;
}
_receiveCallback->OnDroppedFrames(1);
@ -215,8 +215,6 @@ VCMGenericDecoder::VCMGenericDecoder(std::unique_ptr<VideoDecoder> decoder)
VCMGenericDecoder::VCMGenericDecoder(VideoDecoder* decoder, bool isExternal)
: _callback(NULL),
_frameInfos(),
_nextFrameInfoIdx(0),
decoder_(decoder),
_codecType(kVideoCodecGeneric),
_isExternal(isExternal),
@ -249,26 +247,25 @@ int32_t VCMGenericDecoder::InitDecode(const VideoCodec* settings,
int32_t VCMGenericDecoder::Decode(const VCMEncodedFrame& frame, Timestamp now) {
TRACE_EVENT1("webrtc", "VCMGenericDecoder::Decode", "timestamp",
frame.Timestamp());
_frameInfos[_nextFrameInfoIdx].decodeStart = now;
_frameInfos[_nextFrameInfoIdx].renderTimeMs = frame.RenderTimeMs();
_frameInfos[_nextFrameInfoIdx].rotation = frame.rotation();
_frameInfos[_nextFrameInfoIdx].timing = frame.video_timing();
_frameInfos[_nextFrameInfoIdx].ntp_time_ms =
frame.EncodedImage().ntp_time_ms_;
_frameInfos[_nextFrameInfoIdx].packet_infos = frame.PacketInfos();
VCMFrameInformation frame_info;
frame_info.decodeStart = now;
frame_info.renderTimeMs = frame.RenderTimeMs();
frame_info.rotation = frame.rotation();
frame_info.timing = frame.video_timing();
frame_info.ntp_time_ms = frame.EncodedImage().ntp_time_ms_;
frame_info.packet_infos = frame.PacketInfos();
// Set correctly only for key frames. Thus, use latest key frame
// content type. If the corresponding key frame was lost, decode will fail
// and content type will be ignored.
if (frame.FrameType() == VideoFrameType::kVideoFrameKey) {
_frameInfos[_nextFrameInfoIdx].content_type = frame.contentType();
frame_info.content_type = frame.contentType();
_last_keyframe_content_type = frame.contentType();
} else {
_frameInfos[_nextFrameInfoIdx].content_type = _last_keyframe_content_type;
frame_info.content_type = _last_keyframe_content_type;
}
_callback->Map(frame.Timestamp(), &_frameInfos[_nextFrameInfoIdx]);
_callback->Map(frame.Timestamp(), frame_info);
_nextFrameInfoIdx = (_nextFrameInfoIdx + 1) % kDecoderFrameMemoryLength;
int32_t ret = decoder_->Decode(frame.EncodedImage(), frame.MissingFrame(),
frame.RenderTimeMs());
VideoDecoder::DecoderInfo decoder_info = decoder_->GetDecoderInfo();