[FFmpeg-devel] [PATCH] interplayacm: check for too large b

[Paul B Mahol]

On 10/30/16, Andreas Cadhalpun <andreas.cadhalpun at googlemail.com> wrote:
> This fixes out-of-bounds reads.
>
> Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
> ---
>  libavcodec/interplayacm.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/libavcodec/interplayacm.c b/libavcodec/interplayacm.c
> index 0fd3501..0486e00 100644
> --- a/libavcodec/interplayacm.c
> +++ b/libavcodec/interplayacm.c
> @@ -326,6 +326,10 @@ static int t15(InterplayACMContext *s, unsigned ind,
> unsigned col)
>      for (i = 0; i < s->rows; i++) {
>          /* b = (x1) + (x2 * 3) + (x3 * 9) */
>          b = get_bits(gb, 5);
> +        if (b > 26) {
> +            av_log(NULL, AV_LOG_ERROR, "Too large b = %d > 26\n", b);
> +            return AVERROR_INVALIDDATA;
> +        }
>
>          n1 =  (mul_3x3[b] & 0x0F) - 1;
>          n2 = ((mul_3x3[b] >> 4) & 0x0F) - 1;
> @@ -351,6 +355,10 @@ static int t27(InterplayACMContext *s, unsigned ind,
> unsigned col)
>      for (i = 0; i < s->rows; i++) {
>          /* b = (x1) + (x2 * 5) + (x3 * 25) */
>          b = get_bits(gb, 7);
> +        if (b > 124) {
> +            av_log(NULL, AV_LOG_ERROR, "Too large b = %d > 124\n", b);
> +            return AVERROR_INVALIDDATA;
> +        }
>
>          n1 =  (mul_3x5[b] & 0x0F) - 2;
>          n2 = ((mul_3x5[b] >> 4) & 0x0F) - 2;
> @@ -375,6 +383,10 @@ static int t37(InterplayACMContext *s, unsigned ind,
> unsigned col)
>      for (i = 0; i < s->rows; i++) {
>          /* b = (x1) + (x2 * 11) */
>          b = get_bits(gb, 7);
> +        if (b > 120) {
> +            av_log(NULL, AV_LOG_ERROR, "Too large b = %d > 120\n", b);
> +            return AVERROR_INVALIDDATA;
> +        }
>
>          n1 =  (mul_2x11[b] & 0x0F) - 5;
>          n2 = ((mul_2x11[b] >> 4) & 0x0F) - 5;
> --
> 2.10.1
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>

probably ok.