cavsdec: check ff_get_buffer() return value

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC:libav-stable@libav.org

libavcodec/cavsdec.c

@@ -928,6 +928,7 @@ static inline int check_for_slice(AVSContext *h)
 
 static int decode_pic(AVSContext *h)
 {
+    int ret;
     int skip_count    = -1;
     enum cavs_mb mb_type;
 
@@ -964,8 +965,10 @@ static int decode_pic(AVSContext *h)
             skip_bits(&h->gb, 1); //marker_bit
     }
 
-    ff_get_buffer(h->avctx, h->cur.f, h->cur.f->pict_type == AV_PICTURE_TYPE_B ?
-                  0 : AV_GET_BUFFER_FLAG_REF);
+    ret = ff_get_buffer(h->avctx, h->cur.f, h->cur.f->pict_type == AV_PICTURE_TYPE_B ?
+                        0 : AV_GET_BUFFER_FLAG_REF);
+    if (ret < 0)
+        return ret;
 
     if (!h->edge_emu_buffer) {
         int alloc_size = FFALIGN(FFABS(h->cur.f->linesize[0]) + 32, 32);