Validate references of frames inserted into FrameBuffer2.

webrtc/modules/video_coding/frame_buffer2.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 220 matching lines @@
   stopped_ = false;
 }
 
 void FrameBuffer::Stop() {
   TRACE_EVENT0("webrtc", "FrameBuffer::Stop");
   rtc::CritScope lock(&crit_);
   stopped_ = true;
   new_continuous_frame_event_.Set();
 }
 
+bool FrameBuffer::ValidReferences(const FrameObject& frame) const {
+  for (size_t i = 0; i < frame.num_references; ++i) {
+    if (AheadOrAt(frame.references[i], frame.picture_id))
+      return false;
+    for (size_t j = i + 1; j < frame.num_references; ++j) {
+      if (frame.references[i] == frame.references[j])
+        return false;
+    }
+  }
+
+  if (frame.inter_layer_predicted && frame.spatial_layer == 0)
+    return false;
+
+  return true;
+}
+
 void FrameBuffer::UpdatePlayoutDelays(const FrameObject& frame) {
   TRACE_EVENT0("webrtc", "FrameBuffer::UpdatePlayoutDelays");
   PlayoutDelay playout_delay = frame.EncodedImage().playout_delay_;
   if (playout_delay.min_ms >= 0)
     timing_->set_min_playout_delay(playout_delay.min_ms);
 
   if (playout_delay.max_ms >= 0)
     timing_->set_max_playout_delay(playout_delay.max_ms);
 }
 
 int FrameBuffer::InsertFrame(std::unique_ptr<FrameObject> frame) {
   TRACE_EVENT0("webrtc", "FrameBuffer::InsertFrame");
   RTC_DCHECK(frame);
   if (stats_callback_)
     stats_callback_->OnCompleteFrame(frame->num_references == 0, frame->size());
   FrameKey key(frame->picture_id, frame->spatial_layer);
 
   rtc::CritScope lock(&crit_);
 
   int last_continuous_picture_id =
       last_continuous_frame_it_ == frames_.end()
           ? -1
           : last_continuous_frame_it_->first.picture_id;
 
+  if (!ValidReferences(*frame)) {
+    LOG(LS_WARNING) << "Frame with (picture_id:spatial_id) (" << key.picture_id
+                    << ":" << static_cast<int>(key.spatial_layer)
+                    << ") has invalid frame references, dropping frame.";
+    return last_continuous_picture_id;
+  }
+
   if (num_frames_buffered_ >= kMaxFramesBuffered) {
     LOG(LS_WARNING) << "Frame with (picture_id:spatial_id) (" << key.picture_id
                     << ":" << static_cast<int>(key.spatial_layer)
                     << ") could not be inserted due to the frame "
                     << "buffer being full, dropping frame.";
     return last_continuous_picture_id;
   }
 
-  if (frame->inter_layer_predicted && frame->spatial_layer == 0) {
-    LOG(LS_WARNING) << "Frame with (picture_id:spatial_id) (" << key.picture_id
-                    << ":" << static_cast<int>(key.spatial_layer)
-                    << ") is marked as inter layer predicted, dropping frame.";
-    return last_continuous_picture_id;
-  }
-
   if (last_decoded_frame_it_ != frames_.end() &&
       key <= last_decoded_frame_it_->first) {
     if (AheadOf(frame->timestamp, last_decoded_frame_timestamp_) &&
         frame->num_references == 0) {
       // If this frame has a newer timestamp but an earlier picture id then we
       // assume there has been a jump in the picture id due to some encoder
       // reconfiguration or some other reason. Even though this is not according
       // to spec we can still continue to decode from this frame if it is a
       // keyframe.
       LOG(LS_WARNING) << "A jump in picture id was detected, clearing buffer.";
@@ skipping 66 matching lines @@
     auto frame = continuous_frames.front();
     continuous_frames.pop();
 
     if (last_continuous_frame_it_->first < frame->first)
       last_continuous_frame_it_ = frame;
 
     // Loop through all dependent frames, and if that frame no longer has
     // any unfulfilled dependencies then that frame is continuous as well.
     for (size_t d = 0; d < frame->second.num_dependent_frames; ++d) {
       auto frame_ref = frames_.find(frame->second.dependent_frames[d]);
-      --frame_ref->second.num_missing_continuous;
+      RTC_DCHECK(frame_ref != frames_.end());
 
-      if (frame_ref->second.num_missing_continuous == 0) {
-        frame_ref->second.continuous = true;
-        continuous_frames.push(frame_ref);
+      // TODO(philipel): Look into why we've seen this happen.
+      if (frame_ref != frames_.end()) {
+        --frame_ref->second.num_missing_continuous;
+        if (frame_ref->second.num_missing_continuous == 0) {
+          frame_ref->second.continuous = true;
+          continuous_frames.push(frame_ref);
+        }
       }
     }
   }
 }
 
 void FrameBuffer::PropagateDecodability(const FrameInfo& info) {
   TRACE_EVENT0("webrtc", "FrameBuffer::PropagateDecodability");
   RTC_CHECK(info.num_dependent_frames < FrameInfo::kMaxNumDependentFrames);
   for (size_t d = 0; d < info.num_dependent_frames; ++d) {
     auto ref_info = frames_.find(info.dependent_frames[d]);
@@ skipping 138 matching lines @@
   frames_.clear();
   last_decoded_frame_it_ = frames_.end();
   last_continuous_frame_it_ = frames_.end();
   next_frame_it_ = frames_.end();
   num_frames_history_ = 0;
   num_frames_buffered_ = 0;
 }
 
 }  // namespace video_coding
 }  // namespace webrtc