From: Guillaume Nault <g.nault@xxxxxxxxxxxx> 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. Backporting Notes This is a backport of a backport. Fixes: 33f72e6f0c67 ("l2tp : multicast notification to the registered listeners") Signed-off-by: Guillaume Nault <g.nault@xxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Amit Pundir <amit.pundir@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Giuliano Procida <gprocida@xxxxxxxxxx> --- net/l2tp/l2tp_netlink.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c index fb3248ff8b48..43f0af1c4697 100644 --- a/net/l2tp/l2tp_netlink.c +++ b/net/l2tp/l2tp_netlink.c @@ -626,10 +626,12 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf 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); + } } out: -- 2.27.0.rc0.183.gde8f92d652-goog