3.16.63-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Xin Long <[email protected]> commit f8504f4ca0a0e9f84546ef86e00b24d2ea9a0bd2 upstream. 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: f6cd651b056f ("l2tp: fix race in duplicate tunnel detection") Reported-by: Jianlin Shi <[email protected]> Signed-off-by: Xin Long <[email protected]> Reviewed-by: Guillaume Nault <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> --- net/l2tp/l2tp_core.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1627,12 +1627,7 @@ int l2tp_tunnel_register(struct l2tp_tun 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); @@ -1647,6 +1642,10 @@ int l2tp_tunnel_register(struct l2tp_tun 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) { udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP; udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
