bonding: fix bonding_masters race condition in bond unloading

[ Upstream commit 69b0216ac255f523556fa3d4ff030d857eaaa37f ]

While the bonding module is unloading, it is considered that after
rtnl_link_unregister all bond devices are destroyed but since no
synchronization mechanism exists, a new bond device can be created
via bonding_masters before unregister_pernet_subsys which would
lead to multiple problems (e.g. NULL pointer dereference, wrong RIP,
list corruption).

This patch fixes the issue by removing any bond devices left in the
netns after bonding_masters is removed from sysfs.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Acked-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index fc07f90e6d5b9894687f948f652a1bab334c6b6a..2589e57f92ae68bbc44abc2abb671f02b8da2c64 100644 (file)
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -4853,9 +4853,18 @@ static int __net_init bond_net_init(struct net *net)
 static void __net_exit bond_net_exit(struct net *net)
 {
        struct bond_net *bn = net_generic(net, bond_net_id);
+       struct bonding *bond, *tmp_bond;
+       LIST_HEAD(list);
 
        bond_destroy_sysfs(bn);
        bond_destroy_proc_dir(bn);
+
+       /* Kill off any bonds created after unregistering bond rtnl ops */
+       rtnl_lock();
+       list_for_each_entry_safe(bond, tmp_bond, &bn->dev_list, bond_list)
+               unregister_netdevice_queue(bond->dev, &list);
+       unregister_netdevice_many(&list);
+       rtnl_unlock();
 }
 
 static struct pernet_operations bond_net_ops = {