From a21090cff296eb82b6de09304d64de466bdcaefc Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Wed, 7 Oct 2009 03:18:17 -0700 Subject: [PATCH] ipv4: arp_notify address list bug This fixes a bug with arp_notify. If arp_notify is enabled, kernel will crash if address is changed and no IP address is assigned. http://bugzilla.kernel.org/show_bug.cgi?id=14330 Reported-by: Hannes Frederic Sowa Signed-off-by: Stephen Hemminger Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/devinet.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index e92f1fd28aa..5df2f6a0b0f 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -1077,12 +1077,16 @@ static int inetdev_event(struct notifier_block *this, unsigned long event, ip_mc_up(in_dev); /* fall through */ case NETDEV_CHANGEADDR: - if (IN_DEV_ARP_NOTIFY(in_dev)) - arp_send(ARPOP_REQUEST, ETH_P_ARP, - in_dev->ifa_list->ifa_address, - dev, - in_dev->ifa_list->ifa_address, - NULL, dev->dev_addr, NULL); + /* Send gratuitous ARP to notify of link change */ + if (IN_DEV_ARP_NOTIFY(in_dev)) { + struct in_ifaddr *ifa = in_dev->ifa_list; + + if (ifa) + arp_send(ARPOP_REQUEST, ETH_P_ARP, + ifa->ifa_address, dev, + ifa->ifa_address, NULL, + dev->dev_addr, NULL); + } break; case NETDEV_DOWN: ip_mc_down(in_dev); -- 2.20.1