[FFmpeg-devel] [PATCH 3/5] avcodec/cbs_h265_syntax_template:

[James Almer]

On 8/16/2024 8:15 PM, Michael Niedermayer wrote:
> Fixes: Assertion width > 0 && width <= 32 failed
> Fixes: 71012/clusterfuzz-testcase-minimized-ffmpeg_BSF_HEVC_METADATA_fuzzer-6073354744823808
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>   libavcodec/cbs_h265_syntax_template.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c
> index 12fa185c774..d23cb58e863 100644
> --- a/libavcodec/cbs_h265_syntax_template.c
> +++ b/libavcodec/cbs_h265_syntax_template.c
> @@ -2307,6 +2307,10 @@ SEI_FUNC(sei_3d_reference_displays_info, (CodedBitstreamContext *ctx, RWContext
>           else
>               length = FFMAX(0, (int)current->exponent_ref_display_width[i] +
>                                 (int)current->prec_ref_display_width - 31);
> +
> +        if (length > 32)
> +            return AVERROR_PATCHWELCOME;

I guess this error code is fine since CBS currently can't read values > 
32 and this element can be up to 62 bits long.

Maybe also print an error that says something like "refDispWidthBits > 
32 is not supported".

> +
>           if (length)
>               ubs(length, mantissa_ref_display_width[i], 1, i);
>           else
> @@ -2318,6 +2322,10 @@ SEI_FUNC(sei_3d_reference_displays_info, (CodedBitstreamContext *ctx, RWContext
>               else
>                   length = FFMAX(0, (int)current->exponent_ref_viewing_distance[i] +
>                                     (int)current->prec_ref_viewing_dist - 31);
> +
> +            if (length > 32)
> +                return AVERROR_PATCHWELCOME;

Ditto, "refViewDistBits > 32 is not supported".

> +
>               if (length)
>                   ubs(length, mantissa_ref_viewing_distance[i], 1, i);
>               else