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Commit 79272fc2 authored by Xin Long's avatar Xin Long Committed by Greg Kroah-Hartman
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l2tp: fix a sock refcnt leak in l2tp_tunnel_register 



[ Upstream commit f8504f4ca0a0e9f84546ef86e00b24d2ea9a0bd2 ]

This issue happens when trying to add an existent tunnel. It
doesn't call sock_put() before returning -EEXIST to release
the sock refcnt that was held by calling sock_hold() before
the existence check.

This patch is to fix it by holding the sock after doing the
existence check.

Fixes: f6cd651b ("l2tp: fix race in duplicate tunnel detection")
Reported-by: default avatarJianlin Shi <jishi@redhat.com>
Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
Reviewed-by: default avatarGuillaume Nault <g.nault@alphalink.fr>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 115973a6

net/l2tp/l2tp_core.c

+4 −5
Original line number Diff line number Diff line
@@ -1490,12 +1490,7 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 
			goto err_sock;

	}



	sk = sock->sk;



	sock_hold(sk);

	tunnel->sock = sk;

	tunnel->l2tp_net = net;



	pn = l2tp_pernet(net);



	spin_lock_bh(&pn->l2tp_tunnel_list_lock);
@@ -1510,6 +1505,10 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 
	list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);

	spin_unlock_bh(&pn->l2tp_tunnel_list_lock);



	sk = sock->sk;

	sock_hold(sk);

	tunnel->sock = sk;



	if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {

		struct udp_tunnel_sock_cfg udp_cfg = {

			.sk_user_data = tunnel,