[FFmpeg-devel] [PATCH] avcodec/ac3dec: Check expacc

[Michael Niedermayer]

On Thu, Mar 03, 2022 at 06:36:29PM +0100, Paul B Mahol wrote:
> On 11/3/16, Michael Niedermayer <michael at niedermayer.cc> wrote:
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavcodec/ac3dec.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
> > index a95c204..499971a 100644
> > --- a/libavcodec/ac3dec.c
> > +++ b/libavcodec/ac3dec.c
> > @@ -426,6 +426,10 @@ static int decode_exponents(AC3DecodeContext *s,
> >      group_size = exp_strategy + (exp_strategy == EXP_D45);
> >      for (grp = 0, i = 0; grp < ngrps; grp++) {
> >          expacc = get_bits(gbc, 7);
> > +        if (expacc >= 125) {
> > +            av_log(s->avctx, AV_LOG_ERROR, "expacc %d is out-of-range\n",
> > expacc);
> > +            return AVERROR_INVALIDDATA;
> > +        }
> >          dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
> >          dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
> >          dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
> > --
> 
> Please revert this ASAP. It breaks decoding valid files.

please provide an affected file / link to one

thx

[...]
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