Re: [FFmpeg-devel] [PATCH] avcodec/vvc/dec: fix possible null-pointer dereference

[Nuo Mi <nuomi2021-at-gmail.com@ffmpeg.org>]

On Thu, Jun 12, 2025 at 1:53 AM Marvin Scholz <
epirat07-at-gmail.com@ffmpeg.org> wrote:

> When checking for filmgrain here, needs_fg can be true even when
> film_grain_characteristics is NULL (when aom_film_grain.enable is true),
> therefore this check could end up dereferencing film_grain_characteristics
> even though it is NULL.
>
> Fix CID 1648347
>
Thank you, Marvin.
Pushed.

> ---
>  libavcodec/vvc/dec.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/libavcodec/vvc/dec.c b/libavcodec/vvc/dec.c
> index aba31b94fe..7930d64a05 100644
> --- a/libavcodec/vvc/dec.c
> +++ b/libavcodec/vvc/dec.c
> @@ -770,7 +770,8 @@ static int check_film_grain(VVCContext *s,
> VVCFrameContext *fc)
>          !s->avctx->hwaccel;
>
>      if (fc->ref->needs_fg &&
> -        (fc->sei.common.film_grain_characteristics->present &&
> +        (fc->sei.common.film_grain_characteristics &&
> +         fc->sei.common.film_grain_characteristics->present &&
>
>  !ff_h274_film_grain_params_supported(fc->sei.common.film_grain_characteristics->model_id,
>                  fc->ref->frame->format) ||
>              !av_film_grain_params_select(fc->ref->frame))) {
> --
> 2.39.5 (Apple Git-154)
>
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