4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Guillaume Nault <g.nault@xxxxxxxxxxxx>
[ Upstream commit e91793bb615cf6cdd59c0b6749fe173687bb0947 ]
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: 9e9cb6221aa7 ("l2tp: fix userspace reception on plain L2TP sockets")
Signed-off-by: Guillaume Nault <g.nault@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/l2tp/l2tp_ppp.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -450,6 +450,10 @@ static void pppol2tp_session_close(struc
static void pppol2tp_session_destruct(struct sock *sk)
{
struct l2tp_session *session = sk->sk_user_data;
+
+ skb_queue_purge(&sk->sk_receive_queue);
+ skb_queue_purge(&sk->sk_write_queue);
+
if (session) {
sk->sk_user_data = NULL;
BUG_ON(session->magic != L2TP_SESSION_MAGIC);
@@ -488,9 +492,6 @@ static int pppol2tp_release(struct socke
l2tp_session_queue_purge(session);
sock_put(sk);
}
- skb_queue_purge(&sk->sk_receive_queue);
- skb_queue_purge(&sk->sk_write_queue);
-
release_sock(sk);
/* This will delete the session context via