[FFmpeg-devel] [PATCH] avcodec/rscc: Check that the to be uncompressed input is large enough

Paul B Mahol onemda at gmail.com
Mon Apr 1 11:08:10 EEST 2019


On 4/1/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
> On Sun, Mar 31, 2019 at 05:35:33PM +0200, Paul B Mahol wrote:
>> On 3/31/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
>> > Fixes: Out of array access
>> > Fixes:
>> > 13984/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_RSCC_fuzzer-5734128093233152
>> >
>> > Found-by: continuous fuzzing process
>> > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
>> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>> > ---
>> >  libavcodec/rscc.c | 7 +++++++
>> >  1 file changed, 7 insertions(+)
>> >
>> > diff --git a/libavcodec/rscc.c b/libavcodec/rscc.c
>> > index 7d4e842cd3..4adee9d7d4 100644
>> > --- a/libavcodec/rscc.c
>> > +++ b/libavcodec/rscc.c
>> > @@ -199,6 +199,13 @@ static int rscc_decode_frame(AVCodecContext
>> > *avctx,
>> > void *data,
>> >          /* If necessary, uncompress tiles, and hijack the bytestream
>> > reader
>> > */
>> >          if (packed_tiles_size != tiles_nb * TILE_SIZE) {
>> >              uLongf length = tiles_nb * TILE_SIZE;
>> > +
>> > +            if (bytestream2_get_bytes_left(gbc) < packed_tiles_size) {
>> > +                av_log(avctx, AV_LOG_ERROR, "compressed input
>> > truncated\n");
>> > +                ret = AVERROR_INVALIDDATA;
>> > +                goto end;
>> > +            }
>> > +
>> >              inflated_tiles = av_malloc(length);
>> >              if (!inflated_tiles) {
>> >                  ret = AVERROR(ENOMEM);
>> > --
>> > 2.21.0
>> >
>> > _______________________________________________
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>> > ffmpeg-devel at ffmpeg.org
>> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >
>> > To unsubscribe, visit link above, or email
>> > ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>>
>> Please commit without log message.
>
> if you prefer that, sure, will do.
> this will be the only AVERROR_INVALIDDATA case in that file without a log
> message though.

Yes, I prefer without log message.
Printing log messages is also slow.

>
> Thanks
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> It is dangerous to be right in matters on which the established authorities
> are wrong. -- Voltaire
>


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