Andreas Rheinhardt:
> Since the switch to the new FIFO API in commit
> ea511196a6c85eb433e10cdbecb0b2c722faf20d, the FIFO is always
> grown by the amount of data intended to be written into it
> even in case the FIFO has enough free space. Fix this by
> only growing the FIFO if needed and then only by the amount that is
> actually needed.
>
> The allocation errors that resulted from this uncovered another bug:
> The context is left in an inconsistent state in case the FIFO can't
> be grown, because the FIFO does not contain as much data as the sizes
> contained in the PacketDesc list claim. This led to an infinite loop
> in output_packet() (called from mpeg_mux_end()).
>
> Fix this by growing the FIFO before adding a new PacketDesc element,
> thereby preventing the context from becoming inconsistent.
>
> Reported-by: Nicolas Gaullier <nicolas.gaullier@cji.paris>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
> ---
> libavformat/mpegenc.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/libavformat/mpegenc.c b/libavformat/mpegenc.c
> index cc47a43288..62692bfcd1 100644
> --- a/libavformat/mpegenc.c
> +++ b/libavformat/mpegenc.c
> @@ -1152,6 +1152,7 @@ static int mpeg_mux_write_packet(AVFormatContext *ctx,
> AVPacket *pkt)
> int64_t pts, dts;
> PacketDesc *pkt_desc;
> int preload, ret;
> + size_t can_write;
> const int is_iframe = st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
> (pkt->flags & AV_PKT_FLAG_KEY);
>
> @@ -1192,6 +1193,14 @@ static int mpeg_mux_write_packet(AVFormatContext *ctx,
> AVPacket *pkt)
> size -= 3;
> }
>
> + /* Enlarge the FIFO before adding a new PacketDesc
> + * in order to avoid inconsistencies on failure. */
> + can_write = av_fifo_can_write(stream->fifo);
> + if (can_write < size) {
> + ret = av_fifo_grow2(stream->fifo, size - can_write);
> + if (ret < 0)
> + return ret;
> + }
> pkt_desc = av_mallocz(sizeof(PacketDesc));
> if (!pkt_desc)
> return AVERROR(ENOMEM);
> @@ -1207,10 +1216,6 @@ static int mpeg_mux_write_packet(AVFormatContext *ctx,
> AVPacket *pkt)
> pkt_desc->unwritten_size =
> pkt_desc->size = size;
>
> - ret = av_fifo_grow2(stream->fifo, size);
> - if (ret < 0)
> - return ret;
> -
> if (s->is_dvd) {
> // min VOBU length 0.4 seconds (mpucoder)
> if (is_iframe &&
Will apply this tonight unless there are objections.
- Andreas
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