diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 0e275b58151c..1cefea571efd 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1703,6 +1703,11 @@ static int fl_set_enc_opt(struct nlattr **tb, struct fl_flow_key *key,
 			return -EINVAL;
 		}
 		nla_opt_msk = nla_next(nla_opt_msk, &msk_depth);
+
+		if (msk_depth && !nla_ok(nla_opt_msk, msk_depth)) {
+			NL_SET_ERR_MSG(extack, "A mask attribute is invalid");
+			return -EINVAL;
+		}
 	}
 
 	return 0;