[FFmpeg-devel] [PATCH] avcodec/motion_est: Fix xy indexing on range violation in ff_get_best_fcode()

Michael Niedermayer michael at niedermayer.cc
Wed Feb 9 11:36:00 EET 2022


On Wed, Feb 09, 2022 at 03:39:20AM +0100, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > This codepath seems untested, no testcases change
> > 
> > Found-by: <mkver>
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavcodec/motion_est.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/libavcodec/motion_est.c b/libavcodec/motion_est.c
> > index 9c548c1567..4cf1afe888 100644
> > --- a/libavcodec/motion_est.c
> > +++ b/libavcodec/motion_est.c
> > @@ -1621,9 +1621,11 @@ int ff_get_best_fcode(MpegEncContext * s, int16_t (*mv_table)[2], int type)
> >                                       fcode_tab[my + MAX_MV]);
> >                      int j;
> >  
> > -                        if(mx >= range || mx < -range ||
> > -                           my >= range || my < -range)
> > -                            continue;
> > +                    if (mx >= range || mx < -range ||
> > +                        my >= range || my < -range) {
> > +                        xy++;
> > +                        continue;
> > +                    }
> >  
> >                      for(j=0; j<fcode && j<8; j++){
> >                          if(s->pict_type==AV_PICTURE_TYPE_B || s->current_picture.mc_mb_var[xy] < s->current_picture.mb_var[xy])
> 
> It would be simpler if you added the xy++ to the outer-for-loop and
> removed the other xy++.

that leaves the indention wrong. Will move the xy in the for loop and
fix the indention in a separate commit

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When you are offended at any man's fault, turn to yourself and study your
own failings. Then you will forget your anger. -- Epictetus
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