From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikolay Aleksandrov Subject: [PATCHv2 1/2] bonding: fix netdev event NULL pointer dereference Date: Thu, 11 Apr 2013 21:18:55 +0200 Message-ID: <1365707936-5073-2-git-send-email-nikolay@redhat.com> References: <1365707936-5073-1-git-send-email-nikolay@redhat.com> Cc: andy@greyhouse.net, fubar@us.ibm.com, davem@davemloft.net To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48000 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753216Ab3DKTV7 (ORCPT ); Thu, 11 Apr 2013 15:21:59 -0400 In-Reply-To: <1365707936-5073-1-git-send-email-nikolay@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: In commit 471cb5a33dcbd7c529684a2ac7ba4451414ee4a7 ("bonding: remove usage of dev->master") a bug was introduced which causes a NULL pointer dereference. If a bond device is in mode 6 (ALB) and a slave is added it will dereference a NULL pointer in bond_slave_netdev_event(). This is because in bond_enslave we have bond_alb_init_slave() which changes the MAC address of the slave and causes a NETDEV_CHANGEADDR. Then we have in bond_slave_netdev_event(): struct slave *slave = bond_slave_get_rtnl(slave_dev); struct bonding *bond = slave->bond; bond_slave_get_rtnl() dereferences slave_dev->rx_handler_data which at that time is NULL since netdev_rx_handler_register() is called later. This is fixed by checking if slave is NULL before dereferencing it. v2: Comment style changed. Signed-off-by: Nikolay Aleksandrov --- drivers/net/bonding/bond_main.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 171b10f..15c675c 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -3168,11 +3168,20 @@ static int bond_slave_netdev_event(unsigned long event, struct net_device *slave_dev) { struct slave *slave = bond_slave_get_rtnl(slave_dev); - struct bonding *bond = slave->bond; - struct net_device *bond_dev = slave->bond->dev; + struct bonding *bond; + struct net_device *bond_dev; u32 old_speed; u8 old_duplex; + /* A netdev event can be generated while enslaving a device + * before netdev_rx_handler_register is called in which case + * slave will be NULL + */ + if (!slave) + return NOTIFY_DONE; + bond_dev = slave->bond->dev; + bond = slave->bond; + switch (event) { case NETDEV_UNREGISTER: if (bond->setup_by_slave) -- 1.8.1.4