batman-adv: fix kernel crash due to missing NULL checks

commit 354136bcc3c4f40a2813bba8f57ca5267d812d15 upstream.

batadv_softif_vlan_get() may return NULL which has to be verified
by the caller.

Fixes: 35df3b298fc8 ("batman-adv: fix TT VLAN inconsistency on VLAN re-add")
Reported-by: Ryan Thompson <ryan@eero.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 5ec31d7..271a08d 100644 (file)
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -449,6 +449,9 @@ out:
  */
 void batadv_softif_vlan_free_ref(struct batadv_softif_vlan *vlan)
 {
+       if (!vlan)
+               return;
+
        if (atomic_dec_and_test(&vlan->refcount)) {
                spin_lock_bh(&vlan->bat_priv->softif_vlan_list_lock);
                hlist_del_rcu(&vlan->list);

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 07b263a..d41537c 100644 (file)
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -575,6 +575,9 @@ bool batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
 
        /* increase the refcounter of the related vlan */
        vlan = batadv_softif_vlan_get(bat_priv, vid);
+       if (WARN(!vlan, "adding TT local entry %pM to non-existent VLAN %d",
+                addr, BATADV_PRINT_VID(vid)))
+               goto out;
 
        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Creating new local tt entry: %pM (vid: %d, ttvn: %d)\n",
@@ -1047,6 +1050,9 @@ uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
 
        /* decrease the reference held for this vlan */
        vlan = batadv_softif_vlan_get(bat_priv, vid);
+       if (!vlan)
+               goto out;
+
        batadv_softif_vlan_free_ref(vlan);
        batadv_softif_vlan_free_ref(vlan);
 
@@ -1147,8 +1153,10 @@ static void batadv_tt_local_table_free(struct batadv_priv *bat_priv)
                        /* decrease the reference held for this vlan */
                        vlan = batadv_softif_vlan_get(bat_priv,
                                                      tt_common_entry->vid);
-                       batadv_softif_vlan_free_ref(vlan);
-                       batadv_softif_vlan_free_ref(vlan);
+                       if (vlan) {
+                               batadv_softif_vlan_free_ref(vlan);
+                               batadv_softif_vlan_free_ref(vlan);
+                       }
 
                        batadv_tt_local_entry_free_ref(tt_local);
                }
@@ -3188,8 +3196,10 @@ static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
 
                        /* decrease the reference held for this vlan */
                        vlan = batadv_softif_vlan_get(bat_priv, tt_common->vid);
-                       batadv_softif_vlan_free_ref(vlan);
-                       batadv_softif_vlan_free_ref(vlan);
+                       if (vlan) {
+                               batadv_softif_vlan_free_ref(vlan);
+                               batadv_softif_vlan_free_ref(vlan);
+                       }
 
                        batadv_tt_local_entry_free_ref(tt_local);
                }