avcodec/cri: Check length

Fixes: CID1604394 Overflowed constant

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/cri.c

@@ -234,10 +234,14 @@ static int cri_decode_frame(AVCodecContext *avctx, AVFrame *p,
             s->data_size = length;
             goto skip;
         case 105:
+            if (length <= 0)
+                return AVERROR_INVALIDDATA;
             hflip = bytestream2_get_byte(gb) != 0;
             length--;
             goto skip;
         case 106:
+            if (length <= 0)
+                return AVERROR_INVALIDDATA;
             vflip = bytestream2_get_byte(gb) != 0;
             length--;
             goto skip;