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

[Paul B Mahol]

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.