[FFmpeg-devel] [PATCH 1/3] avformat/oggdec: Initialize return value from ogg_read_page() and check it everywhere

[Lynne]

Jun 6, 2020, 19:08 by michael at niedermayer.cc:

> Fixes regression since 9ad47762c17d2c6d06595aa17b88112baa91b72c
> Fixes: out of array access
> Fixes: 22172/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5658535590625280
>
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavformat/oggdec.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
> index b4ba00df61..f65013f55e 100644
> --- a/libavformat/oggdec.c
> +++ b/libavformat/oggdec.c
> @@ -412,6 +412,7 @@ static int ogg_read_page(AVFormatContext *s, int *sid, int probing)
>  if (idx < 0)
>  av_free(readout_buf);
>  avio_seek(bc, start_pos, SEEK_SET);
> +        *sid = -1;
>  return 0;
>  }
>  
> @@ -422,6 +423,7 @@ static int ogg_read_page(AVFormatContext *s, int *sid, int probing)
>  if (idx < 0)
>  av_free(readout_buf);
>  avio_seek(bc, start_pos, SEEK_SET);
> +        *sid = -1;
>  return 0;
>  }
>  
> @@ -661,7 +663,7 @@ static int ogg_get_length(AVFormatContext *s)
>  ogg->page_pos = -1;
>  
>  while (!ogg_read_page(s, &i, 1)) {
> -        if (ogg->streams[i].granule != -1 && ogg->streams[i].granule != 0 &&
> +        if (i >= 0 && ogg->streams[i].granule != -1 && ogg->streams[i].granule != 0 &&
>  ogg->streams[i].codec) {
>  s->streams[i]->duration =
>  ogg_gptopts(s, i, ogg->streams[i].granule, NULL);
>

Took me a while to analyze.
LGTM.