[FFmpeg-devel] [PATCH v2] avcodec/vp9: avoid using uninitialized mutex/condition

[Steve Lhomme]

v2: shorter commit lines and removed an extra space, now I realize it's 
the wrong one, the original being also wrong...

On 2021-09-02 11:19, Steve Lhomme wrote:
> When using slice decoding vp9_free_entries() is called before
> vp9_alloc_entries() is ever called. It should destroy properly
> initialized variables (or check it was never called before).
> 
> It usually works undetected as pthread implementations allows NULL as a
> special value (and should return EINVAL but doesn't). But pthreadGC2
> doesn't allow NULL in pthread_mutex_destroy() and crashes when that's
> the case.
> ---
>   libavcodec/vp9.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c
> index 874005a5ae..8a3d82da09 100644
> --- a/libavcodec/vp9.c
> +++ b/libavcodec/vp9.c
> @@ -42,7 +42,7 @@
>   static void vp9_free_entries(AVCodecContext *avctx) {
>       VP9Context *s = avctx->priv_data;
>   
> -    if (avctx->active_thread_type & FF_THREAD_SLICE)  {
> +    if (avctx->active_thread_type & FF_THREAD_SLICE) {
>           pthread_mutex_destroy(&s->progress_mutex);
>           pthread_cond_destroy(&s->progress_cond);
>           av_freep(&s->entries);
> @@ -1796,6 +1796,10 @@ static av_cold int vp9_decode_init(AVCodecContext *avctx)
>   
>       s->last_bpp = 0;
>       s->s.h.filter.sharpness = -1;
> +    if (avctx->active_thread_type & FF_THREAD_SLICE)  {
> +        pthread_mutex_init(&s->progress_mutex, NULL);
> +        pthread_cond_init(&s->progress_cond, NULL);
> +    }
>   
>       for (int i = 0; i < 3; i++) {
>           s->s.frames[i].tf.f = av_frame_alloc();
> -- 
> 2.29.2
> 
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