Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=68365458a4252fa993b91a00f7a0b18fed399f0d
Commit: 68365458a4252fa993b91a00f7a0b18fed399f0d
Parent: d4782c323d10d3698b71b6a6b3c7bdad33824658
Author: Patrick McHardy <[EMAIL PROTECTED]>
AuthorDate: Sun Jan 20 17:25:14 2008 -0800
Committer: David S. Miller <[EMAIL PROTECTED]>
CommitDate: Sun Jan 20 20:31:45 2008 -0800
[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 <[EMAIL PROTECTED]>
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
drivers/net/veth.c | 14 +-------------
net/core/rtnetlink.c | 5 ++++-
2 files changed, 5 insertions(+), 14 deletions(-)
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 43af9e9..3f67a29 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -459,19 +459,7 @@ static __init int veth_init(void)
static __exit void veth_exit(void)
{
- struct veth_priv *priv, *next;
-
- rtnl_lock();
- /*
- * cannot trust __rtnl_link_unregister() to unregister all
- * devices, as each ->dellink call will remove two devices
- * from the list at once.
- */
- list_for_each_entry_safe(priv, next, &veth_list, list)
- veth_dellink(priv->dev);
-
- __rtnl_link_unregister(&veth_link_ops);
- rtnl_unlock();
+ rtnl_link_unregister(&veth_link_ops);
}
module_init(veth_init);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index e1ba26f..fed95a3 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);
-
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