net: vlan: fix memory leak in vlan_info_rcu_free()

The following leak is reported by kmemleak:

[   86.812073] kmemleak: Found object by alias at 0xffff88006ecc76f0
[   86.816019] Pid: 739, comm: kworker/u:1 Not tainted 3.9.0-rc5+ #842
[   86.816019] Call Trace:
[   86.816019]  <IRQ>  [<ffffffff81151c58>] find_and_get_object+0x8c/0xdf
[   86.816019]  [<ffffffff8190e90d>] ? vlan_info_rcu_free+0x33/0x49
[   86.816019]  [<ffffffff81151cbe>] delete_object_full+0x13/0x2f
[   86.816019]  [<ffffffff8194bbb6>] kmemleak_free+0x26/0x45
[   86.816019]  [<ffffffff8113e8c7>] slab_free_hook+0x1e/0x7b
[   86.816019]  [<ffffffff81141c05>] kfree+0xce/0x14b
[   86.816019]  [<ffffffff8190e90d>] vlan_info_rcu_free+0x33/0x49
[   86.816019]  [<ffffffff810d0b0b>] rcu_do_batch+0x261/0x4e7

The reason is that in vlan_info_rcu_free() we don't take the VLAN protocol
into account when iterating over the vlan_devices_array.
Reported-by: NCong Wang <amwang@redhat.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Tested-by: NCong Wang <amwang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/8021q/vlan_core.c

@@ -157,10 +157,11 @@ EXPORT_SYMBOL(vlan_untag);
 
 static void vlan_group_free(struct vlan_group *grp)
 {
-	int i;
+	int i, j;
 
-	for (i = 0; i < VLAN_GROUP_ARRAY_SPLIT_PARTS; i++)
-		kfree(grp->vlan_devices_arrays[i]);
+	for (i = 0; i < VLAN_PROTO_NUM; i++)
+		for (j = 0; j < VLAN_GROUP_ARRAY_SPLIT_PARTS; j++)
+			kfree(grp->vlan_devices_arrays[i][j]);
 }
 
 static void vlan_info_free(struct vlan_info *vlan_info)