[FFmpeg-devel] [PATCH] avcodec/notchlc: Check available space for luma block code

[Michael Niedermayer]

On Sun, Sep 13, 2020 at 12:39:34AM +0200, Paul B Mahol wrote:
> On Sat, Sep 12, 2020 at 06:43:30PM +0200, Michael Niedermayer wrote:
> > Fixes: Timeout (too long -> 2sec)
> > Fixes: 25439/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_NOTCHLC_fuzzer-5688211127664640
> > 
> > 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/notchlc.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/libavcodec/notchlc.c b/libavcodec/notchlc.c
> > index 3f7079da70..e7e69b0c21 100644
> > --- a/libavcodec/notchlc.c
> > +++ b/libavcodec/notchlc.c
> > @@ -229,6 +229,9 @@ static int decode_blocks(AVCodecContext *avctx, AVFrame *p, ThreadFrame *frame,
> >      bytestream2_seek(&rgb, s->y_data_row_offsets, SEEK_SET);
> >      bytestream2_seek(gb, s->y_control_data_offset, SEEK_SET);
> >  
> > +    if ((avctx->height + 3) / 4 * ((avctx->width + 3) / 4) * 4 > bytestream2_get_bytes_left(gb))
> > +        return AVERROR_INVALIDDATA;
> > +
> >      dsty = (uint16_t *)p->data[0];
> >      dsta = (uint16_t *)p->data[3];
> >      ylinesize = p->linesize[0] / 2;
> > -- 
> > 2.17.1
> 
> Is this correct at all?

Its the amount that is read from gb in the next loop just below the added 
check

thx

> 
> If you do not like timeouts than get smaller samples or reduce dimensions of accepted files.
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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

There will always be a question for which you do not know the correct answer.
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