@@ -510,6 +510,8 @@ static int shorten_decode_frame(AVCodecContext *avctx, void *data,

                 break;

             case FN_BITSHIFT:

                 s->bitshift = get_ur_golomb_shorten(&s->gb, BITSHIFTSIZE);

+                if (s->bitshift < 0)

+                    return AVERROR_INVALIDDATA;

                 break;

             case FN_BLOCKSIZE: {

                 unsigned blocksize = get_uint(s, av_log2(s->blocksize));