Index: if_bridge.c
===================================================================
RCS file: /cvs/src/sys/net/if_bridge.c,v
retrieving revision 1.307
diff -u -p -r1.307 if_bridge.c
--- if_bridge.c	19 Feb 2018 08:59:52 -0000	1.307
+++ if_bridge.c	19 Apr 2018 01:30:53 -0000
@@ -361,6 +361,11 @@ bridge_ioctl(struct ifnet *ifp, u_long c
 			error = ENOENT;
 			break;
 		}
+		if (ifs->if_type != IFT_ETHER &&
+		    ifs->if_type != IFT_MPLSTUNNEL) {
+			error = EINVAL;
+			break;
+		}
 		if (ifs->if_bridgeport != NULL) {
 			error = EBUSY;
 			break;