[FFmpeg-devel] [PATCH 1/2] avcodec/agm: Test remaining data in decode_raw_intra_rgb()

[Michael Niedermayer]

On Sun, Feb 09, 2020 at 01:55:00PM +0000, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Fixes: Timeout (270sec -> 25ms)
> > Fixes: 20485/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AGM_fuzzer-5636954207289344
> > 
> > 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/agm.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/libavcodec/agm.c b/libavcodec/agm.c
> > index 80f4697ee5..957131648b 100644
> > --- a/libavcodec/agm.c
> > +++ b/libavcodec/agm.c
> > @@ -573,6 +573,9 @@ static int decode_raw_intra_rgb(AVCodecContext *avctx, GetByteContext *gbyte, AV
> >      uint8_t *dst = frame->data[0] + (avctx->height - 1) * frame->linesize[0];
> >      uint8_t r = 0, g = 0, b = 0;
> >  
> > +    if (bytestream2_get_bytes_left(gbyte) < 3 * avctx->width * avctx->height)
> 
> Can the multiplication on the right overflow?

ff_set_dimensions() and others check for the dimensions not being too
large. So if they can overflow then there needs to be a bug elsewhere


> 
> > +        return AVERROR_INVALIDDATA;
> > +
> >      for (int y = 0; y < avctx->height; y++) {
> >          for (int x = 0; x < avctx->width; x++) {
> >              dst[x*3+0] = bytestream2_get_byte(gbyte) + r;
> 
> After one has checked once that enough data is present, one can use
> the unchecked bytestream2-API here and for the other two reads.

will do

thx

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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