[PATCH 4.9 048/172] l2tp: hold session while sending creation notifications

Greg Kroah-Hartman
2017-07-03T13:33:48Z

From: Guillaume Nault <g.nault@alphalink.fr>

commit 5e6a9e5a3554a5b3db09cdc22253af1849c65dff upstream.

l2tp_session_find() doesn't take any reference on the returned session.
Therefore, the session may disappear while sending the notification.

Use l2tp_session_get() instead and decrement session's refcount once
the notification is sent.

Fixes: 33f72e6f0c67 ("l2tp : multicast notification to the registered listeners")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/l2tp/l2tp_netlink.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -634,10 +634,12 @@ static int l2tp_nl_cmd_session_create(st
session_id, peer_session_id, &cfg);

if (ret >= 0) {
- session = l2tp_session_find(net, tunnel, session_id);
- if (session)
+ session = l2tp_session_get(net, tunnel, session_id, false);
+ if (session) {
ret = l2tp_session_notify(&l2tp_nl_family, info, session,
L2TP_CMD_SESSION_CREATE);
+ l2tp_session_dec_refcount(session);
+ }
}