From fc75fc8339e7727167443469027540b283daac71 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 22 Dec 2010 04:39:39 +0000 Subject: [PATCH] ipv4: dont create routes on down devices In ip_route_output_slow(), instead of allowing a route to be created on a not UPed device, report -ENETUNREACH immediately. # ip tunnel add mode ipip remote 10.16.0.164 local 10.16.0.72 dev eth0 # (Note : tunl1 is down) # ping -I tunl1 10.1.2.3 PING 10.1.2.3 (10.1.2.3) from 192.168.18.5 tunl1: 56(84) bytes of data. (nothing) # ./a.out tunl1 # ip tunnel del tunl1 Message from syslogd@shelby at Dec 22 10:12:08 ... kernel: unregister_netdevice: waiting for tunl1 to become free. Usage count = 3 After patch: # ping -I tunl1 10.1.2.3 connect: Network is unreachable Reported-by: Nicolas Dichtel Signed-off-by: Eric Dumazet Reviewed-by: Octavian Purdila Signed-off-by: David S. Miller --- net/ipv4/route.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 987bf9adb31..df948b0f1ac 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2585,9 +2585,10 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp, goto out; /* RACE: Check return value of inet_select_addr instead. */ - if (rcu_dereference(dev_out->ip_ptr) == NULL) - goto out; /* Wrong error code */ - + if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) { + err = -ENETUNREACH; + goto out; + } if (ipv4_is_local_multicast(oldflp->fl4_dst) || ipv4_is_lbcast(oldflp->fl4_dst)) { if (!fl.fl4_src) -- 2.39.2