l2tp: hold tunnel while handling genl tunnel updates

We need to make sure the tunnel is not going to be destroyed by
l2tp_tunnel_destruct() concurrently.

Fixes: 309795f4bec2 ("l2tp: Add netlink control API for L2TP")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index 808966550620a7f6ed4461b11f997b8daae49111..d61e75b4e619972b0746faaaba4d3d3e3c22b353 100644 (file)
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -303,8 +303,8 @@ static int l2tp_nl_cmd_tunnel_modify(struct sk_buff *skb, struct genl_info *info
        }
        tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);
 
-       tunnel = l2tp_tunnel_find(net, tunnel_id);
-       if (tunnel == NULL) {
+       tunnel = l2tp_tunnel_get(net, tunnel_id);
+       if (!tunnel) {
                ret = -ENODEV;
                goto out;
        }
@@ -315,6 +315,8 @@ static int l2tp_nl_cmd_tunnel_modify(struct sk_buff *skb, struct genl_info *info
        ret = l2tp_tunnel_notify(&l2tp_nl_family, info,
                                 tunnel, L2TP_CMD_TUNNEL_MODIFY);
 
+       l2tp_tunnel_dec_refcount(tunnel);
+
 out:
        return ret;
 }