[src/trunk]: src/sys/net Avoid temporal dangling reference

[ozaki-r <ozaki-r%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/696dbe272c4d
branches:  trunk
changeset: 818646:696dbe272c4d
user:      ozaki-r <ozaki-r%NetBSD.org@localhost>
date:      Fri Oct 21 03:04:33 2016 +0000

description:
Avoid temporal dangling reference

diffstat:

 sys/net/route.c |  18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

diffs (44 lines):

diff -r 03e3a6775010 -r 696dbe272c4d sys/net/route.c
--- a/sys/net/route.c   Thu Oct 20 23:16:23 2016 +0000
+++ b/sys/net/route.c   Fri Oct 21 03:04:33 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: route.c,v 1.175 2016/10/18 07:30:30 ozaki-r Exp $      */
+/*     $NetBSD: route.c,v 1.176 2016/10/21 03:04:33 ozaki-r Exp $      */
 
 /*-
  * Copyright (c) 1998, 2008 The NetBSD Foundation, Inc.
@@ -97,7 +97,7 @@
 #endif
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: route.c,v 1.175 2016/10/18 07:30:30 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: route.c,v 1.176 2016/10/21 03:04:33 ozaki-r Exp $");
 
 #include <sys/param.h>
 #ifdef RTFLUSH_DEBUG
@@ -962,16 +962,20 @@
 int
 rt_setgate(struct rtentry *rt, const struct sockaddr *gate)
 {
+       struct sockaddr *new, *old;
 
        KASSERT(rt->_rt_key != NULL);
        RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
 
-       if (rt->rt_gateway != NULL)
-               sockaddr_free(rt->rt_gateway);
-       KASSERT(rt->_rt_key != NULL);
-       RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);
-       if ((rt->rt_gateway = sockaddr_dup(gate, M_ZERO | M_NOWAIT)) == NULL)
+       new = sockaddr_dup(gate, M_ZERO | M_NOWAIT);
+       if (new == NULL)
                return ENOMEM;
+
+       old = rt->rt_gateway;
+       rt->rt_gateway = new;
+       if (old != NULL)
+               sockaddr_free(old);
+
        KASSERT(rt->_rt_key != NULL);
        RT_DPRINTF("rt->_rt_key = %p\n", (void *)rt->_rt_key);