Do not even try to dereference a NULL pointer.

Found the hard way by Peter N. M. Hansteen.

ok claudio@, phessler@

diff --git a/sys/net/route.c b/sys/net/route.c
index 90ad7f1..74deb67 100644 (file)
--- a/sys/net/route.c
+++ b/sys/net/route.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: route.c,v 1.199 2015/01/13 12:14:00 mpi Exp $ */
+/*     $OpenBSD: route.c,v 1.200 2015/01/18 14:51:43 mpi Exp $ */
 /*     $NetBSD: route.c,v 1.14 1996/02/13 22:00:46 christos Exp $      */
 
 /*
@@ -1045,8 +1045,10 @@ rt_checkgate(struct ifnet *ifp, struct rtentry *rt, struct sockaddr *dst,
 
        if ((rt->rt_flags & RTF_UP) == 0) {
                rt = rtalloc(dst, RT_REPORT|RT_RESOLVE, rtableid);
+               if (rt == NULL)
+                       return (EHOSTUNREACH);
                rt->rt_refcnt--;
-               if (rt == NULL || rt->rt_ifp != ifp)
+               if (rt->rt_ifp != ifp)
                        return (EHOSTUNREACH);
        }