l2tp: hold tunnel while processing genl delete command

l2tp_nl_cmd_tunnel_delete() needs to take a reference on the tunnel, to
prevent it from being concurrently freed by l2tp_tunnel_destruct().

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>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index 27ee94b5c189..808966550620 100644
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -273,8 +273,8 @@ static int l2tp_nl_cmd_tunnel_delete(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;
         }
@@ -284,6 +284,8 @@ static int l2tp_nl_cmd_tunnel_delete(struct sk_buff *skb, struct genl_info *info
 
         (void) l2tp_tunnel_delete(tunnel);
 
+        l2tp_tunnel_dec_refcount(tunnel);
+
 out:
         return ret;
 }