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l2tp: fix a sock refcnt leak in l2tp_tunnel_register

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[ Upstream commit f8504f4ca0 ]

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: f6cd651b05 ("l2tp: fix race in duplicate tunnel detection")
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xin Long 2018-11-13 01:08:25 +08:00 • committed by Greg Kroah-Hartman
commit 79272fc2c1
1 changed files with 4 additions and 5 deletions
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9
net/l2tp/l2tp_core.c
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@ -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,