Index: sys/net/if_vlan.c
===================================================================
--- sys/net/if_vlan.c
+++ sys/net/if_vlan.c
@@ -570,10 +570,17 @@
 
 	VLAN_XLOCK_ASSERT();
 
+	if (ifp->if_flags & IFF_DYING)
+		return (ENXIO);
+
 	/* Find the parent. */
 	sc = ifp->if_softc;
 	ifp_p = PARENT(sc);
 
+	/* check if parent is freed */
+	if (ifp_p == NULL)
+		return (ENXIO);
+
 	CURVNET_SET_QUIET(ifp_p->if_vnet);
 
 	/* First, remove any existing filter entries. */