lavf/matroskaenc: Fix memory leak after write trailer

Fix memory leak after write trailer for #7827, only store a audio
packet whose buffer has size greater than zero in cur_audio_pkt.

Audio packets with size zero, but with side-data currently lead to
memleaks, in the Matroska muxer, because they are not properly freed:

They are currently put into an AVPacket in the MatroskaMuxContext to
ensure that the necessary audio is always available for a new cluster,
but are only written and freed when their size is > 0.

As the only use we have for such packets consists in updating the
CodecPrivate it makes no sense to store these packets at all and this
is how this commit solves the memleak.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@googlemail.com>
Signed-off-by: Jun Zhao <barryjzhao@tencent.com>

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index b9f99c4463925fa4e84268177aa7f512d53093a6..06f3aeb46db0251473a6907bb7c01d27eb5c91bd 100644 (file)
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -2534,7 +2534,8 @@ static int mkv_write_packet(AVFormatContext *s, AVPacket *pkt)
     // buffer an audio packet to ensure the packet containing the video
     // keyframe's timecode is contained in the same cluster for WebM
     if (codec_type == AVMEDIA_TYPE_AUDIO) {
-        ret = av_packet_ref(&mkv->cur_audio_pkt, pkt);
+        if (pkt->size > 0)
+            ret = av_packet_ref(&mkv->cur_audio_pkt, pkt);
     } else
         ret = mkv_write_packet_internal(s, pkt, 0);
     return ret;