l2tp: purge socket queues in the .destruct() callback

The Rx path may grab the socket right before pppol2tp_release(), but
nothing guarantees that it will enqueue packets before
skb_queue_purge(). Therefore, the socket can be destroyed without its
queues fully purged.

Fix this by purging queues in pppol2tp_session_destruct() where we're
guaranteed nothing is still referencing the socket.

Fixes: 9e9cb6221a ("l2tp: fix userspace reception on plain L2TP sockets")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Guillaume Nault 2017-03-29 08:45:29 +02:00 committed by David S. Miller
parent 94d7ee0baa
commit e91793bb61

View File

@ -450,6 +450,10 @@ static void pppol2tp_session_close(struct l2tp_session *session)
static void pppol2tp_session_destruct(struct sock *sk) static void pppol2tp_session_destruct(struct sock *sk)
{ {
struct l2tp_session *session = sk->sk_user_data; struct l2tp_session *session = sk->sk_user_data;
skb_queue_purge(&sk->sk_receive_queue);
skb_queue_purge(&sk->sk_write_queue);
if (session) { if (session) {
sk->sk_user_data = NULL; sk->sk_user_data = NULL;
BUG_ON(session->magic != L2TP_SESSION_MAGIC); BUG_ON(session->magic != L2TP_SESSION_MAGIC);
@ -488,9 +492,6 @@ static int pppol2tp_release(struct socket *sock)
l2tp_session_queue_purge(session); l2tp_session_queue_purge(session);
sock_put(sk); sock_put(sk);
} }
skb_queue_purge(&sk->sk_receive_queue);
skb_queue_purge(&sk->sk_write_queue);
release_sock(sk); release_sock(sk);
/* This will delete the session context via /* This will delete the session context via