From: Guillaume Nault <[email protected]>

commit 8c0e421525c9eb50d68e8f633f703ca31680b746 upstream.

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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Giuliano Procida <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 net/l2tp/l2tp_netlink.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -310,8 +310,8 @@ static int l2tp_nl_cmd_tunnel_modify(str
        }
        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;
        }
@@ -322,6 +322,8 @@ static int l2tp_nl_cmd_tunnel_modify(str
        ret = l2tp_tunnel_notify(&l2tp_nl_family, info,
                                 tunnel, L2TP_CMD_TUNNEL_MODIFY);
 
+       l2tp_tunnel_dec_refcount(tunnel);
+
 out:
        return ret;
 }


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