net: l2tp_eth: fix kernel panic on rmmod l2tp_eth

[ Upstream commit a06998b88b1651c5f71c0e35f528bf2057188ead ]

We must prevent module unloading if some devices are still attached to
l2tp_eth driver.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Denys Fedoryshchenko <denys@visp.net.lb>
Tested-by: Denys Fedoryshchenko <denys@visp.net.lb>
Cc: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index d2726a7..3c55f63 100644 (file)
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -167,6 +167,7 @@ static void l2tp_eth_delete(struct l2tp_session *session)
                if (dev) {
                        unregister_netdev(dev);
                        spriv->dev = NULL;
+                       module_put(THIS_MODULE);
                }
        }
 }
@@ -254,6 +255,7 @@ static int l2tp_eth_create(struct net *net, u32 tunnel_id, u32 session_id, u32 p
        if (rc < 0)
                goto out_del_dev;
 
+       __module_get(THIS_MODULE);
        /* Must be done after register_netdev() */
        strlcpy(session->ifname, dev->name, IFNAMSIZ);