[FFmpeg-devel] [PATCH] avcodec/h263dec: Check against previous dimensions instead of coded
Kacper Michajlow
kasper93 at gmail.com
Thu Jan 30 10:15:23 EET 2025
On Thu, 30 Jan 2025 at 02:57, Michael Niedermayer
<michael at niedermayer.cc> wrote:
>
> Fixes: out of array access
> Fixes: crash-a41ef3db699013f669b076f02f36942925f5a98c
>
> Found-by: Kacper Michajlow <kasper93 at gmail.com>
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
> libavcodec/h263dec.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
> index 0c23012584e..5eefdc4602b 100644
> --- a/libavcodec/h263dec.c
> +++ b/libavcodec/h263dec.c
> @@ -431,6 +431,7 @@ int ff_h263_decode_frame(AVCodecContext *avctx, AVFrame *pict,
> MpegEncContext *s = avctx->priv_data;
> int ret;
> int slice_ret = 0;
> + int bak_width, bak_height;
>
> /* no supplementary picture */
> if (buf_size == 0) {
> @@ -482,6 +483,9 @@ retry:
> if (ret < 0)
> return ret;
>
> + bak_width = s->width;
> + bak_height = s->height;
> +
> /* let's go :-) */
> if (CONFIG_WMV2_DECODER && s->msmpeg4_version == MSMP4_WMV2) {
> ret = ff_wmv2_decode_picture_header(s);
> @@ -501,11 +505,12 @@ retry:
> }
>
> if (ret < 0 || ret == FRAME_SKIPPED) {
> - if ( s->width != avctx->coded_width
> - || s->height != avctx->coded_height) {
> + if ( s->width != bak_width
> + || s->height != bak_height) {
> av_log(s->avctx, AV_LOG_WARNING, "Reverting picture dimensions change due to header decoding failure\n");
> - s->width = avctx->coded_width;
> - s->height= avctx->coded_height;
> + s->width = bak_width;
> + s->height= bak_height;
> +
> }
> }
> if (ret == FRAME_SKIPPED)
> --
> 2.48.1
>
Works for me. Thanks.
- Kacper
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