[FFmpeg-devel] [PATCH 6/7] avformat/lxfdec: Fix multiple integer overflows related to track_size

[Tomas Härdin]

tor 2021-01-14 klockan 23:51 +0100 skrev Michael Niedermayer:
> Fixes: signed integer overflow: 538976288 * 8 cannot be represented in type 'int'
> Fixes: 26910/clusterfuzz-testcase-minimized-ffmpeg_dem_LXF_fuzzer-6634030636335104
> 
> 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/lxfdec.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/lxfdec.c b/libavformat/lxfdec.c
> index fa84ceea78..509d19fe7f 100644
> --- a/libavformat/lxfdec.c
> +++ b/libavformat/lxfdec.c
> @@ -195,7 +195,7 @@ static int get_packet_header(AVFormatContext *s)
>              return AVERROR_PATCHWELCOME;
>          }
>  
> -        samples = track_size * 8 / st->codecpar->bits_per_coded_sample;
> +        samples = track_size * 8LL / st->codecpar->bits_per_coded_sample;
>  
>          //use audio packet size to determine video standard
>          //for NTSC we have one 8008-sample audio frame per five video frames
> @@ -210,6 +210,8 @@ static int get_packet_header(AVFormatContext *s)
>              avpriv_set_pts_info(s->streams[0], 64, 1, 25);
>          }
>  
> +        if (av_popcount(channels) * (uint64_t)track_size > INT_MAX)
> +            return AVERROR_INVALIDDATA;
>          //TODO: warning if track mask != (1 << channels) - 1?
>          ret = av_popcount(channels) * track_size;

What happens if channels == 0 ? Probably gets caught in
av_new_packet(), just making sure

/Tomas