[FFmpeg-devel] [FFmpeg-cvslog] avcodec/bitstream: Check for integer code truncation in build_table()

[Carl Eugen Hoyos]

Am Fr., 14. Juni 2019 um 21:40 Uhr schrieb Michael Niedermayer
<git at videolan.org>:
>
> ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Wed Jun  5 12:18:54 2019 +0200| [e78b0f83748f92ea9e93b21c36082e0dd04d7cb1] | committer: Michael Niedermayer
>
> avcodec/bitstream: Check for integer code truncation in build_table()
>
> Fixes: out of array read
> Fixes: 14563/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AGM_fuzzer-5646451545210880
>
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>
> > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=e78b0f83748f92ea9e93b21c36082e0dd04d7cb1
> ---
>
>  libavcodec/bitstream.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/libavcodec/bitstream.c b/libavcodec/bitstream.c
> index 8762e5f4b2..590b490527 100644
> --- a/libavcodec/bitstream.c
> +++ b/libavcodec/bitstream.c
> @@ -226,6 +226,10 @@ static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
>              /* note: realloc has been done, so reload tables */
>              table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
>              table[j][0] = index; //code
> +            if (table[j][0] != index) {

> +                avpriv_request_sample(NULL, "strange codes");

This broke building with --enable-hardcoded-tables, patch sent.

Carl Eugen