On Thu, Apr 15, 2021 at 7:18 AM Sishuai Gong <sish...@purdue.edu> wrote:
> diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
> index 203890e378cb..879f1264ec3c 100644
> --- a/net/l2tp/l2tp_core.c
> +++ b/net/l2tp/l2tp_core.c
> @@ -1478,6 +1478,9 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel,
> struct net *net,
> tunnel->l2tp_net = net;
> pn = l2tp_pernet(net);
>
> + sk = sock->sk;
> + tunnel->sock = sk;
> +
> spin_lock_bh(&pn->l2tp_tunnel_list_lock);
> list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) {
> if (tunnel_walk->tunnel_id == tunnel->tunnel_id) {
> @@ -1490,9 +1493,7 @@ 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;
I think you have to hold this refcnt before making tunnel->sock visible
to others.
Why not just move this together and simply release the refcnt on error
path?
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 203890e378cb..8eb805ee18d4 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1478,11 +1478,15 @@ int l2tp_tunnel_register(struct l2tp_tunnel
*tunnel, struct net *net,
tunnel->l2tp_net = net;
pn = l2tp_pernet(net);
+ sk = sock->sk;
+ sock_hold(sk);
+ tunnel->sock = sk;
+
spin_lock_bh(&pn->l2tp_tunnel_list_lock);
list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) {
if (tunnel_walk->tunnel_id == tunnel->tunnel_id) {
spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
-
+ sock_put(sk);
ret = -EEXIST;
goto err_sock;
}
@@ -1490,10 +1494,6 @@ 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,
