Re: [FFmpeg-devel] [PATCH 1/3] avcodec/siren: prevent getbitcontext overread

[Peter Ross]

On Sat, Sep 18, 2021 at 08:01:38PM +1000, Peter Ross wrote:
> ---
>  libavcodec/siren.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/libavcodec/siren.c b/libavcodec/siren.c
> index 2161b29a2c..3b0ad7b642 100644
> --- a/libavcodec/siren.c
> +++ b/libavcodec/siren.c
> @@ -608,12 +608,16 @@ static int decode_vector(SirenContext *s, int 
> number_of_regions,
>  
>                  index >>= 1;
>  
> -                if (error == 0 && get_bits_left(gb) >= 0) {
> +                if (error == 0) {
>                      for (j = 0; j < vector_dimension[category]; j++) {
>                          decoded_value = mlt_quant[category][index & ((1 << 
> index_table[category]) - 1)];
>                          index >>= index_table[category];
>  
>                          if (decoded_value) {
> +                            if (get_bits_left(gb) <= 0) {
> +                                error = 1;
> +                                break;
> +                            }
>                              if (!get_bits1(gb))
>                                  decoded_value *= 
> -decoder_standard_deviation[region];
>                              else

ping

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)

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