[FFmpeg-devel] [PATCH] libavcodec/h264dec: avoid arithmetic on null pointers

[Anton Khirnov]

Quoting Jeremy Dorfman (2023-03-01 19:50:08)
> null pointer arithmetic is undefined behavior in C.
> ---
>  libavcodec/h264dec.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c
> index 2d691731c5..ef698f2630 100644
> --- a/libavcodec/h264dec.c
> +++ b/libavcodec/h264dec.c
> @@ -912,8 +912,8 @@ static int finalize_frame(H264Context *h, AVFrame *dst, H264Picture *out, int *g
>              av_log(h->avctx, AV_LOG_DEBUG, "Duplicating field %d to fill missing\n", field);
>  
>              for (p = 0; p<4; p++) {
> -                dst_data[p] = f->data[p] + (field^1)*f->linesize[p];
> -                src_data[p] = f->data[p] +  field   *f->linesize[p];
> +                dst_data[p] = f->data[p] ? f->data[p] + (field^1)*f->linesize[p] : NULL;
> +                src_data[p] = f->data[p] ? f->data[p] +  field   *f->linesize[p] : NULL;

Why would that be NULL? Seems like something that should not happen.

-- 
Anton Khirnov