--- a/sys/netgraph7/ng_fec.c
+++ b/sys/netgraph7/ng_fec.c
@@ -1285,10 +1285,20 @@
 	case NGM_FEC_COOKIE:
 		switch (msg->header.cmd) {
 		case NGM_FEC_ADD_IFACE:
+			if (msg->header.arglen < 2 ||
+			    memchr(msg->data, '\0', msg->header.arglen) == NULL) {
+				error = EINVAL;
+				break;
+			}
 			ifname = msg->data;
 			error = ng_fec_addport(priv, ifname);
 			break;
 		case NGM_FEC_DEL_IFACE:
+			if (msg->header.arglen < 2 ||
+			    memchr(msg->data, '\0', msg->header.arglen) == NULL) {
+				error = EINVAL;
+				break;
+			}
 			ifname = msg->data;
 			error = ng_fec_delport(priv, ifname);
 			break;