On Fri, Oct 27, 2023 at 10:07:38AM +0200, Dawid Kozinski/Multimedia (PLT) /SRPOL/Staff Engineer/Samsung Electronics wrote:
> 
> 
> 
> 
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> > Michael Niedermayer
> > Sent: czwartek, 5 października 2023 00:59
> > To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
> > Subject: [FFmpeg-devel] [PATCH 2/4] avcodec/evc_parse: Check
> > num_remaining_tiles_in_slice_minus1
> > 
> > Fixes: out of array access
> > Fixes: 62467/clusterfuzz-testcase-minimized-
> > ffmpeg_BSF_EVC_FRAME_MERGE_fuzzer-6092990982258688
> > 
> > Found-by: continuous fuzzing process
> > https://protect2.fireeye.com/v1/url?k=10fdc12a-701f5c77-10fc4a65-
> > 000babd9f1ba-c93ee30773aca891&q=1&e=409cddd0-bda7-445c-b76b-
> > 1caf069ec3f8&u=https%3A%2F%2Fgithub.com%2Fgoogle%2Foss-
> > fuzz%2Ftree%2Fmaster%2Fprojects%2Fffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavcodec/evc_parse.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/libavcodec/evc_parse.c b/libavcodec/evc_parse.c index
> > bd3a4416f2d..5ab33166cf3 100644
> > --- a/libavcodec/evc_parse.c
> > +++ b/libavcodec/evc_parse.c
> > @@ -58,8 +58,12 @@ int ff_evc_parse_slice_header(GetBitContext *gb,
> > EVCParserSliceHeader *sh,
> >          if (!sh->arbitrary_slice_flag)
> >              sh->last_tile_id = get_bits(gb, pps->tile_id_len_minus1 + 1);
> >          else {
> > -            sh->num_remaining_tiles_in_slice_minus1 =
> get_ue_golomb_long(gb);
> > -            num_tiles_in_slice = sh->num_remaining_tiles_in_slice_minus1
> + 2;
> > +            unsigned num_remaining_tiles_in_slice_minus1 =
> > get_ue_golomb_long(gb);
> > +            if (num_remaining_tiles_in_slice_minus1 > EVC_MAX_TILE_ROWS *
> > EVC_MAX_TILE_COLUMNS - 2)
> > +                return AVERROR_INVALIDDATA;
> > +
> > +            num_tiles_in_slice = num_remaining_tiles_in_slice_minus1 + 2;
> > +            sh->num_remaining_tiles_in_slice_minus1 =
> > + num_remaining_tiles_in_slice_minus1;
> >              for (int i = 0; i < num_tiles_in_slice - 1; ++i)
> >                  sh->delta_tile_id_minus1[i] = get_ue_golomb_long(gb);
> >          }
> > --
> > 2.17.1
> > 
> 
> Reviewed and tested. It can be merged.

will apply

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Homeopathy is like voting while filling the ballot out with transparent ink.
Sometimes the outcome one wanted occurs. Rarely its worse than filling out
a ballot properly.