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[03/27] l2tp: hold session while sending creation notifications

Message ID 20200521235740.191338-4-gprocida@google.com
State New
Headers show
Series [01/27] l2tp: lock socket before checking flags in connect() | expand

Commit Message

Giuliano Procida May 21, 2020, 11:57 p.m. UTC 
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.

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@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>
Signed-off-by: Giuliano Procida <gprocida@google.com>
---
 net/l2tp/l2tp_netlink.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
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Patch

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: