[PATCH 5.10.y] batman-adv: clean untagged VLAN on netdev registration failure

[Sven Eckelmann <sven@narfation.org>]

commit 8669a550c752d86baebc5fdc83b8ff35c4372c0e upstream.

When an mesh interface is registered, it creates an untagged struct
batadv_meshif_vlan on top of it via the NETDEV_REGISTER notifier. But in
this process, another receiver of this notification can veto the
registration. The netdev registration will be aborted because of this veto.

The register_netdevice() call will try to clean up the net_device using
unregister_netdevice_queue() - which only uses the .priv_destructor to
free private resources. In this situation, .dellink will not be called.

The cleanup of the untagged batadv_meshif_vlan must thefore be done in the
destructor to avoid a leak of this object.

Cc: stable@vger.kernel.org
Fixes: 5d2c05b21337 ("batman-adv: add per VLAN interface attribute framework")
[ switch to old "mesh_iface" name "soft_iface", Context ]
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 net/batman-adv/main.c           |  8 ++++++++
 net/batman-adv/soft-interface.c | 13 ++-----------
 net/batman-adv/soft-interface.h |  2 ++
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 70c373f5572e3..7210f82cbc786 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -265,6 +265,7 @@ int batadv_mesh_init(struct net_device *soft_iface)
 void batadv_mesh_free(struct net_device *soft_iface)
 {
 	struct batadv_priv *bat_priv = netdev_priv(soft_iface);
+	struct batadv_softif_vlan *vlan;
 
 	atomic_set(&bat_priv->mesh_state, BATADV_MESH_DEACTIVATING);
 
@@ -280,6 +281,13 @@ void batadv_mesh_free(struct net_device *soft_iface)
 
 	batadv_mcast_free(bat_priv);
 
+	/* destroy the "untagged" VLAN */
+	vlan = batadv_softif_vlan_get(bat_priv, BATADV_NO_FLAGS);
+	if (vlan) {
+		batadv_softif_destroy_vlan(bat_priv, vlan);
+		batadv_softif_vlan_put(vlan);
+	}
+
 	/* Free the TT and the originator tables only after having terminated
 	 * all the other depending components which may use these structures for
 	 * their purposes.
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index c8c62b0cd54c7..bef8d82c3b65f 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -625,8 +625,8 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
  * @bat_priv: the bat priv with all the soft interface information
  * @vlan: the object to remove
  */
-static void batadv_softif_destroy_vlan(struct batadv_priv *bat_priv,
-				       struct batadv_softif_vlan *vlan)
+void batadv_softif_destroy_vlan(struct batadv_priv *bat_priv,
+				struct batadv_softif_vlan *vlan)
 {
 	/* explicitly remove the associated TT local entry because it is marked
 	 * with the NOPURGE flag
@@ -1130,9 +1130,7 @@ void batadv_softif_destroy_sysfs(struct net_device *soft_iface)
 static void batadv_softif_destroy_netlink(struct net_device *soft_iface,
 					  struct list_head *head)
 {
-	struct batadv_priv *bat_priv = netdev_priv(soft_iface);
 	struct batadv_hard_iface *hard_iface;
-	struct batadv_softif_vlan *vlan;
 
 	list_for_each_entry(hard_iface, &batadv_hardif_list, list) {
 		if (hard_iface->soft_iface == soft_iface)
@@ -1140,13 +1138,6 @@ static void batadv_softif_destroy_netlink(struct net_device *soft_iface,
 							BATADV_IF_CLEANUP_KEEP);
 	}
 
-	/* destroy the "untagged" VLAN */
-	vlan = batadv_softif_vlan_get(bat_priv, BATADV_NO_FLAGS);
-	if (vlan) {
-		batadv_softif_destroy_vlan(bat_priv, vlan);
-		batadv_softif_vlan_put(vlan);
-	}
-
 	batadv_sysfs_del_meshif(soft_iface);
 	unregister_netdevice_queue(soft_iface, head);
 }
diff --git a/net/batman-adv/soft-interface.h b/net/batman-adv/soft-interface.h
index 53aba17b90688..2be563c54b0f2 100644
--- a/net/batman-adv/soft-interface.h
+++ b/net/batman-adv/soft-interface.h
@@ -25,6 +25,8 @@ void batadv_softif_destroy_sysfs(struct net_device *soft_iface);
 bool batadv_softif_is_valid(const struct net_device *net_dev);
 extern struct rtnl_link_ops batadv_link_ops;
 int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid);
+void batadv_softif_destroy_vlan(struct batadv_priv *bat_priv,
+				struct batadv_softif_vlan *vlan);
 void batadv_softif_vlan_release(struct kref *ref);
 struct batadv_softif_vlan *batadv_softif_vlan_get(struct batadv_priv *bat_priv,
 						  unsigned short vid);
-- 
2.47.3