linux/net/l2tp
Sabrina Dubroca 62b982eeb4 l2tp: fix race condition in l2tp_tunnel_delete
If we try to delete the same tunnel twice, the first delete operation
does a lookup (l2tp_tunnel_get), finds the tunnel, calls
l2tp_tunnel_delete, which queues it for deletion by
l2tp_tunnel_del_work.

The second delete operation also finds the tunnel and calls
l2tp_tunnel_delete. If the workqueue has already fired and started
running l2tp_tunnel_del_work, then l2tp_tunnel_delete will queue the
same tunnel a second time, and try to free the socket again.

Add a dead flag to prevent firing the workqueue twice. Then we can
remove the check of queue_work's result that was meant to prevent that
race but doesn't.

Reproducer:

    ip l2tp add tunnel tunnel_id 3000 peer_tunnel_id 4000 local 192.168.0.2 remote 192.168.0.1 encap udp udp_sport 5000 udp_dport 6000
    ip l2tp add session name l2tp1 tunnel_id 3000 session_id 1000 peer_session_id 2000
    ip link set l2tp1 up
    ip l2tp del tunnel tunnel_id 3000
    ip l2tp del tunnel tunnel_id 3000

Fixes: f8ccac0e44 ("l2tp: put tunnel socket release on a workqueue")
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-09-26 10:24:34 -07:00
..
Kconfig l2tp: Call udp_sock_create 2014-07-14 16:12:15 -07:00
l2tp_core.c l2tp: fix race condition in l2tp_tunnel_delete 2017-09-26 10:24:34 -07:00
l2tp_core.h l2tp: fix race condition in l2tp_tunnel_delete 2017-09-26 10:24:34 -07:00
l2tp_debugfs.c net, l2tp: convert l2tp_tunnel.ref_count from atomic_t to refcount_t 2017-07-04 22:35:15 +01:00
l2tp_eth.c l2tp: pass tunnel pointer to ->session_create() 2017-09-03 11:04:21 -07:00
l2tp_ip6.c l2tp: fix race in l2tp_recv_common() 2017-04-01 20:16:41 -07:00
l2tp_ip.c l2tp: fix race in l2tp_recv_common() 2017-04-01 20:16:41 -07:00
l2tp_netlink.c l2tp: pass tunnel pointer to ->session_create() 2017-09-03 11:04:21 -07:00
l2tp_ppp.c l2tp: ensure sessions are freed after their PPPOL2TP socket 2017-09-25 14:44:41 -07:00
Makefile l2tp: introduce L2TPv3 IP encapsulation support for IPv6 2012-05-01 09:30:55 -04:00