Quoting Michael Niedermayer (2022-04-01 12:46:08)
> This ignores >64bit
> Alternatively we could support that if it occurs in reality
>
> Fixes: negation of -9223372036854775808
> Fixes: integer overflows
> Fixes:
> 46072/clusterfuzz-testcase-minimized-ffmpeg_dem_MATROSKA_fuzzer-5029840966778880
>
> Found-by: continuous fuzzing process
> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
> ---
> libavformat/matroskadec.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
> index d97fc33d44..069fba6cf7 100644
> --- a/libavformat/matroskadec.c
> +++ b/libavformat/matroskadec.c
> @@ -2886,11 +2886,14 @@ static int matroska_parse_tracks(AVFormatContext *s)
> mkv_stereo_mode_display_mul(track->video.stereo_mode,
> &display_width_mul, &display_height_mul);
>
> if (track->video.display_unit <
> MATROSKA_VIDEO_DISPLAYUNIT_UNKNOWN) {
> - av_reduce(&st->sample_aspect_ratio.num,
> - &st->sample_aspect_ratio.den,
> - st->codecpar->height * track->video.display_width
> * display_width_mul,
> - st->codecpar->width * track->video.display_height
> * display_height_mul,
> - INT_MAX);
> + if (track->video.display_width &&
> track->video.display_height &&
> + st->codecpar->height * (int64_t)display_width_mul <
> INT64_MAX / track->video.display_width &&
> + st->codecpar->width * (int64_t)display_height_mul <
> INT64_MAX / track->video.display_height)
Why not move display_{width,height}_mul to the other side of the
comparison and avoid wordsize assumptions? This is header parsing, so
division performance impact should be negligible.
--
Anton Khirnov
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