From ee6154e11eeccd4ae32c4881415dbd902a869592 Mon Sep 17 00:00:00 2001 From: Nikolay Aleksandrov Date: Wed, 26 Feb 2014 14:20:30 +0100 Subject: [PATCH] bonding: fix a div error caused by the slave release path There's a bug in the slave release function which leads the transmit functions which use the bond->slave_cnt to a div by 0 because we might just have released our last slave and made slave_cnt == 0 but at the same time we may have a transmitter after the check for an empty list which will fetch it and use it in the slave id calculation. Fix it by moving the slave_cnt after synchronize_rcu so if this was our last slave any new transmitters will see an empty slave list which is checked after rcu lock but before calling the mode transmit functions which rely on bond->slave_cnt. Fixes: 278b208375 ("bonding: initial RCU conversion") CC: Veaceslav Falico CC: Andy Gospodarek CC: Jay Vosburgh CC: David S. Miller Signed-off-by: Nikolay Aleksandrov Acked-by: Veaceslav Falico Signed-off-by: David S. Miller --- drivers/net/bonding/bond_main.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 82b70ff1fd28..b47fa0421e01 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -1659,9 +1659,6 @@ static int __bond_release_one(struct net_device *bond_dev, return -EINVAL; } - /* release the slave from its bond */ - bond->slave_cnt--; - bond_sysfs_slave_del(slave); bond_upper_dev_unlink(bond_dev, slave_dev); @@ -1743,6 +1740,7 @@ static int __bond_release_one(struct net_device *bond_dev, unblock_netpoll_tx(); synchronize_rcu(); + bond->slave_cnt--; if (!bond_has_slaves(bond)) { call_netdevice_notifiers(NETDEV_CHANGEADDR, bond->dev); -- 2.20.1