[FFmpeg-devel] [PATCH 03/25] avcodec/magicyuv: Improve overread check when parsing Huffman tables

[Paul B Mahol]

On Sat, Sep 26, 2020 at 12:27:42PM +0200, Andreas Rheinhardt wrote:
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
>  libavcodec/magicyuv.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 

lgtm

> diff --git a/libavcodec/magicyuv.c b/libavcodec/magicyuv.c
> index b56d3e9d32..d2f6a9b01e 100644
> --- a/libavcodec/magicyuv.c
> +++ b/libavcodec/magicyuv.c
> @@ -394,8 +394,13 @@ static int build_huffman(AVCodecContext *avctx, GetBitContext *gbit, int max)
>      while (get_bits_left(gbit) >= 8) {
>          int b = get_bits(gbit, 1);
>          int x = get_bits(gbit, 7);
> -        int l = get_bitsz(gbit, b * 8) + 1;
> +        int l = 1;
>  
> +        if (b) {
> +            if (get_bits_left(gbit) < 8)
> +                break;
> +            l += get_bits(gbit, 8);
> +        }
>          k = j + l;
>          if (k > max || x == 0 || x > 32) {
>              av_log(avctx, AV_LOG_ERROR, "Invalid Huffman codes\n");
> -- 
> 2.25.1
> 
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