batman-adv: Fix memory leak on tt add with invalid vlan

The object tt_local is allocated with kmalloc and not initialized when the
function batadv_tt_local_add checks for the vlan. But this function can
only cleanup the object when the (not yet initialized) reference counter of
the object is 1. This is unlikely and thus the object would leak when the
vlan could not be found.

Instead the uninitialized object tt_local has to be freed manually and the
pointer has to set to NULL to avoid calling the function which would try to
decrement the reference counter of the not existing object.

CID: 1316518
Fixes: 354136bcc3c4 ("batman-adv: fix kernel crash due to missing NULL checks")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 5e953297d3b2bda513cd9ad90e7e634928f34a20..5809b39c1922320e8dbb353de212b472199c796d 100644 (file)
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -595,8 +595,11 @@ 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)))
+                addr, BATADV_PRINT_VID(vid))) {
+               kfree(tt_local);
+               tt_local = NULL;
                goto out;
+       }
 
        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Creating new local tt entry: %pM (vid: %d, ttvn: %d)\n",