Check number of nalus in packet before checking nalu types.

Bug: chromium:840536
Change-Id: Ia4dcf322ad6290691fd01b58fb02cd868714c92e
Reviewed-on: https://webrtc-review.googlesource.com/77121
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23283}

modules/video_coding/packet_buffer.cc

@@ -306,6 +306,10 @@ std::vector<std::unique_ptr<RtpFrameObject>> PacketBuffer::FindFrames(
         if (is_h264 && !is_h264_keyframe) {
           const RTPVideoHeaderH264& header =
               data_buffer_[start_index].video_header.codecHeader.H264;
+
+          if (header.nalus_length >= kMaxNalusPerPacket)
+            return found_frames;
+
           for (size_t j = 0; j < header.nalus_length; ++j) {
             if (header.nalus[j].type == H264::NaluType::kSps) {
               has_h264_sps = true;