From 68365458a4252fa993b91a00f7a0b18fed399f0d Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Sun, 20 Jan 2008 17:25:14 -0800 Subject: [NET]: rtnl_link: fix use-after-free When unregistering the rtnl_link_ops, all existing devices using the ops are destroyed. With nested devices this may lead to a use-after-free despite the use of for_each_netdev_safe() in case the upper device is next in the device list and is destroyed by the NETDEV_UNREGISTER notifier. The easy fix is to restart scanning the device list after removing a device. Alternatively we could add new devices to the front of the list to avoid having dependant devices follow the device they depend on. A third option would be to only restart scanning if dev->iflink of the next device matches dev->ifindex of the current one. For now this seems like the safest solution. With this patch, the veth rtnl_link_ops unregistration can use rtnl_link_unregister() directly since it now also handles destruction of multiple devices at once. Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- net/core/rtnetlink.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'net') diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index e1ba26fb4bf2..fed95a323b28 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -308,9 +308,12 @@ void __rtnl_link_unregister(struct rtnl_link_ops *ops) struct net *net; for_each_net(net) { +restart: for_each_netdev_safe(net, dev, n) { - if (dev->rtnl_link_ops == ops) + if (dev->rtnl_link_ops == ops) { ops->dellink(dev); + goto restart; + } } } list_del(&ops->list); -- cgit v1.2.3-59-g8ed1b