[FFmpeg-devel] [PATCH] avformat/flacenc: Fix memleak when writing attached pictures fails

Andreas Rheinhardt andreas.rheinhardt at gmail.com
Wed Nov 25 03:27:12 EET 2020


Andreas Rheinhardt:
> The FLAC muxer currently stores an attached picture corresponding to an
> AVStream in AVStream.priv_data. The AVPacket contained therein is
> unreferenced after it has been written. The AVPacket structure itself is
> then freed generically as AVStream.priv_data.
> 
> And this can lead to memleaks if an attached picture is not written:
> It might be because the trailer is never written or because writing
> a previous attached picture failed in case error_recognition is set
> to explode.
> 
> Therefore free the packets properly (i.e. with av_packet_free())
> in the muxer's deinit function.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
> I intend to make muxers use AVStream.attached_pic in the medium term
> [1]; then this code can be removed again. I am just sending this now in
> order not to leave a memleak open and to have something easy to
> backport.
> 
> [1]: https://github.com/mkver/FFmpeg/commit/f4513d613b3abf427d042687ba3ae1d2120f3fa3
> 
>  libavformat/flacenc.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/libavformat/flacenc.c b/libavformat/flacenc.c
> index 6b8ce8d7ee..1c983486aa 100644
> --- a/libavformat/flacenc.c
> +++ b/libavformat/flacenc.c
> @@ -347,6 +347,8 @@ static void flac_deinit(struct AVFormatContext *s)
>      FlacMuxerContext *c = s->priv_data;
>  
>      avpriv_packet_list_free(&c->queue, &c->queue_end);
> +    for (unsigned i = 0; i < s->nb_streams; i++)
> +        av_packet_free((AVPacket **)&s->streams[i]->priv_data);
>  }
>  
>  static int flac_write_packet(struct AVFormatContext *s, AVPacket *pkt)
> 
Will apply tomorrow unless there are objections.

- Andreas


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