Index: sys/netinet/in.c
===================================================================
--- sys/netinet/in.c
+++ sys/netinet/in.c
@@ -936,6 +936,7 @@
 {
 	register struct ifaddr *ifa;
 	u_long t;
+	int found = 0;
 
 	if (in.s_addr == INADDR_BROADCAST ||
 	    in.s_addr == INADDR_ANY)
@@ -948,6 +949,7 @@
 	 * with a broadcast address.
 	 */
 #define ia ((struct in_ifaddr *)ifa)
+	if_addr_rlock(ifp);
 	TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
 		if (ifa->ifa_addr->sa_family == AF_INET &&
 		    (in.s_addr == ia->ia_broadaddr.sin_addr.s_addr ||
@@ -962,9 +964,12 @@
 		      * only exist when an interface gets a secondary
 		      * address.
 		      */
-		    ia->ia_subnetmask != (u_long)0xffffffff)
-			    return (1);
-	return (0);
+		    ia->ia_subnetmask != (u_long)0xffffffff) {
+			    found = 1;
+			    break;
+		}
+	if_addr_runlock(ifp);
+	return (found);
 #undef ia
 }