l2tp: don't BUG_ON sk_socket being NULL

It is valid for an existing struct sock object to have a NULL sk_socket
pointer, so don't BUG_ON in l2tp_tunnel_del_work if that should occur.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 8 deletions

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 45373fee38c5..e841ef2a68a5 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1412,19 +1412,21 @@ static void l2tp_tunnel_del_work(struct work_struct *work)
                 return;
 
         sock = sk->sk_socket;
-        BUG_ON(!sock);
 
-        /* If the tunnel socket was created directly by the kernel, use the
-         * sk_* API to release the socket now.  Otherwise go through the
-         * inet_* layer to shut the socket down, and let userspace close it.
+        /* If the tunnel socket was created by userspace, then go through the
+         * inet layer to shut the socket down, and let userspace close it.
+         * Otherwise, if we created the socket directly within the kernel, use
+         * the sk API to release it here.
          * In either case the tunnel resources are freed in the socket
          * destructor when the tunnel socket goes away.
          */
-        if (sock->file == NULL) {
-                kernel_sock_shutdown(sock, SHUT_RDWR);
-                sk_release_kernel(sk);
+        if (tunnel->fd >= 0) {
+                if (sock)
+                        inet_shutdown(sock, 2);
         } else {
-                inet_shutdown(sock, 2);
+                if (sock)
+                        kernel_sock_shutdown(sock, SHUT_RDWR);
+                sk_release_kernel(sk);
         }
 
         l2tp_tunnel_sock_put(sk);