avcodec/cuviddec: check for av_buffer_ref() failure

Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/cuviddec.c

@@ -553,6 +553,12 @@ static int cuvid_output_frame(AVCodecContext *avctx, AVFrame *frame)
 
             tmp_frame->format        = AV_PIX_FMT_CUDA;
             tmp_frame->hw_frames_ctx = av_buffer_ref(ctx->hwframe);
+            if (!tmp_frame->hw_frames_ctx) {
+                ret = AVERROR(ENOMEM);
+                av_frame_free(&tmp_frame);
+                goto error;
+            }
+
             tmp_frame->width         = avctx->width;
             tmp_frame->height        = avctx->height;