[FFmpeg-devel] [PATCH v2 2/3] Fix leaks in tee muxer when open_slave fails

[Marton Balint]

On Thu, 24 Mar 2016, Jan Sebechlebsky wrote:

> Calling close_slave in case error is to be returned from open_slave
> will free allocated resources.
>
> Since failure can happen before bsfs array is initialized,
> close_slave must check that bsfs is not NULL before accessing
> tee_slave->bsfs[i] element.
>
> Signed-off-by: Jan Sebechlebsky <sebechlebskyjan at gmail.com>
> ---
> libavformat/tee.c | 22 ++++++++++++++--------
> 1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/libavformat/tee.c b/libavformat/tee.c
> index 09551b3..e43ef08 100644
> --- a/libavformat/tee.c
> +++ b/libavformat/tee.c
> @@ -141,12 +141,14 @@ static void close_slave(TeeSlave* tee_slave)
>     unsigned i;
>
>     avf = tee_slave->avf;
> -    for (i=0; i < avf->nb_streams; ++i) {
> -        AVBitStreamFilterContext *bsf_next, *bsf = tee_slave->bsfs[i];
> -        while (bsf) {
> -            bsf_next = bsf->next;
> -            av_bitstream_filter_close(bsf);
> -            bsf = bsf_next;
> +    if (tee_slave->bsfs) {
> +        for (i=0; i < avf->nb_streams; ++i) {
> +            AVBitStreamFilterContext *bsf_next, *bsf = tee_slave->bsfs[i];
> +            while (bsf) {
> +                bsf_next = bsf->next;
> +                av_bitstream_filter_close(bsf);
> +                bsf = bsf_next;
> +            }
>         }
>     }
>     av_freep(&tee_slave->stream_map);
> @@ -198,6 +200,7 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
>     ret = avformat_alloc_output_context2(&avf2, NULL, format, filename);
>     if (ret < 0)
>         goto end;
> +    tee_slave->avf = avf2;
>     av_dict_copy(&avf2->metadata, avf->metadata, 0);
>     avf2->opaque   = avf->opaque;
>     avf2->io_open  = avf->io_open;
> @@ -277,7 +280,6 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
>         goto end;
>     }
> 
> -    tee_slave->avf = avf2;
>     tee_slave->bsfs = av_calloc(avf2->nb_streams, sizeof(TeeSlave));
>     if (!tee_slave->bsfs) {
>         ret = AVERROR(ENOMEM);
> @@ -292,7 +294,8 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
>                 av_log(avf, AV_LOG_ERROR,
>                        "Specifier separator in '%s' is '%c', but only characters '%s' "
>                        "are allowed\n", entry->key, *spec, slave_bsfs_spec_sep);
> -                return AVERROR(EINVAL);
> +                ret = AVERROR(EINVAL);
> +                goto end;
>             }
>             spec++; /* consume separator */
>         }
> @@ -337,6 +340,9 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
>     }
> 
> end:
> +    if ( ret < 0 ){
> +        close_slave(tee_slave);
> +    }

Do you really need to call close_slave here? As far as I see if 
open_slave fails then the failure path of tee_write_header will call 
close_slaves, so the streams will be closed, therefore no need to do it 
here.

Regards,
Marton