From: Xin Long Date: Mon, 12 Nov 2018 17:08:25 +0000 (+0800) Subject: l2tp: fix a sock refcnt leak in l2tp_tunnel_register X-Git-Tag: v4.20-rc4~25^2~25 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=f8504f4ca0a0e9f84546ef86e00b24d2ea9a0bd2;p=linux.git l2tp: fix a sock refcnt leak in l2tp_tunnel_register 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 Signed-off-by: Xin Long Reviewed-by: Guillaume Nault Signed-off-by: David S. Miller --- diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 82cdf9020b53..26f1d435696a 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -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,