Re: [PATCH net] l2tp: fix use-after-free during module unload
From: Sergei Shtylyov <hidden>
Date: 2016-08-30 17:51:08
Hello. On 08/30/2016 05:05 PM, Sabrina Dubroca wrote:
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_net_exit() by first flushing the tunnel removal workqueue, and
The patch tells me the function is named l2tp_exit_net(). :-)
quoted hunk ↗ jump to hunk
then waiting for RCU callbacks to complete. Fixes: 167eb17e0b17 ("l2tp: create tunnel sockets in the right namespace") Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> --- net/l2tp/l2tp_core.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 1e40dacaa137..a2ed3bda4ddc 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c@@ -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 = {
MBR, Sergei