[FFmpeg-devel] [PATCH v4] avcodec/decode: validate hw_frames_ctx when AVHWAccel.free_frame_priv is used

[Lynne]

Nov 21, 2023, 05:38 by dmitry.v.rogozhkin-at-intel.com at ffmpeg.org:

> Validate that a hw_frames_ctx is available before using it for
> the AVHWAccel.free_frame_priv callback, and don't require it to
> be present when the callback is not in use by the HWAccel.
>
> v2: check for free_frame_priv (Hendrik)
> v3: return EINVAL (Christoph Reiter)
> v4: better commit message (Hendrik)
>
> See[1]: https://github.com/msys2/MINGW-packages/pull/19050
> Fixes: be07145109 ("avcodec: add AVHWAccel.free_frame_priv callback")
> CC: Lynne <dev at lynne.ee>
> CC: Christoph Reiter <reiter.christoph at gmail.com>
> Signed-off-by: Dmitry Rogozhkin <dmitry.v.rogozhkin at intel.com>
> ---
>  libavcodec/decode.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/libavcodec/decode.c b/libavcodec/decode.c
> index ad39021..50c3995 100644
> --- a/libavcodec/decode.c
> +++ b/libavcodec/decode.c
> @@ -1838,17 +1838,25 @@ int ff_copy_palette(void *dst, const AVPacket *src, void *logctx)
>  int ff_hwaccel_frame_priv_alloc(AVCodecContext *avctx, void **hwaccel_picture_private)
>  {
>  const FFHWAccel *hwaccel = ffhwaccel(avctx->hwaccel);
> -    AVHWFramesContext *frames_ctx;
>  
>  if (!hwaccel || !hwaccel->frame_priv_data_size)
>  return 0;
>  
>  av_assert0(!*hwaccel_picture_private);
>  
> -    frames_ctx = (AVHWFramesContext *)avctx->hw_frames_ctx->data;
> -    *hwaccel_picture_private = ff_refstruct_alloc_ext(hwaccel->frame_priv_data_size, 0,
> -                                                      frames_ctx->device_ctx,
> -                                                      hwaccel->free_frame_priv);
> +    if (hwaccel->free_frame_priv) {
> +        AVHWFramesContext *frames_ctx;
> +
> +        if (!avctx->hw_frames_ctx)
> +            return AVERROR(EINVAL);
> +
> +        *hwaccel_picture_private = ff_refstruct_alloc_ext(hwaccel->frame_priv_data_size, 0,
> +                                                          frames_ctx->device_ctx,
> +                                                          hwaccel->free_frame_priv);
> +    } else {
> +        *hwaccel_picture_private = ff_refstruct_allocz(hwaccel->frame_priv_data_size);
> +    }
> +
>  if (!*hwaccel_picture_private)
>  return AVERROR(ENOMEM);
>

You never set frames_ctx in this patch.