4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Xin Long lucien.xin@gmail.com
[ 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: f6cd651b056f ("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 --- 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 @@ -1490,12 +1490,7 @@ 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); @@ -1510,6 +1505,10 @@ 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) { struct udp_tunnel_sock_cfg udp_cfg = { .sk_user_data = tunnel,