unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
1
Fork 0
Code Pull requests 5 Wiki Activity

l2tp: fix use-after-free during module unload

Browse source 
Tunnel deletion is delayed by both a workqueue (l2tp_tunnel_delete -> wq
 -> l2tp_tunnel_del_work) and RCU (sk_destruct -> RCU ->
l2tp_tunnel_destruct).

By the time l2tp_tunnel_destruct() runs to destroy the tunnel and finish
destroying the socket, the private data reserved via the net_generic
mechanism has already been freed, but l2tp_tunnel_destruct() actually
uses this data.

Make sure tunnel deletion for the netns has completed before returning
from l2tp_exit_net() by first flushing the tunnel removal workqueue, and
then waiting for RCU callbacks to complete.

Fixes: 167eb17e0b ("l2tp: create tunnel sockets in the right namespace")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sabrina Dubroca 2016-09-02 10:22:54 +02:00 committed by David S. Miller
parent ab34380162
commit 2f86953e74
1 changed files with 3 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
net/l2tp/l2tp_core.c
View file

@ -1855,6 +1855,9 @@ static __net_exit void l2tp_exit_net(struct net *net)
(void)l2tp_tunnel_delete(tunnel);
}
rcu_read_unlock_bh();
flush_workqueue(l2tp_wq);
rcu_barrier();
}
static struct pernet_operations l2tp_net_ops = {