macvlan: Fix device ref leak when purging bc_queue

When a parent macvlan device is destroyed we end up purging its
broadcast queue without dropping the device reference count on
the packet source device.  This causes the source device to linger.

This patch drops that reference count.

Fixes: 260916dfb48c ("macvlan: Fix potential use-after free for...")
Reported-by: Joe Ghalam <Joe.Ghalam@dell.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 9261722960a719a8e6d46f4ea5b39f500a0817e8..b34eaaae03fd3f289aab4a90b11c05c587858ad2 100644 (file)
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -1139,6 +1139,7 @@ static int macvlan_port_create(struct net_device *dev)
 static void macvlan_port_destroy(struct net_device *dev)
 {
        struct macvlan_port *port = macvlan_port_get_rtnl(dev);
+       struct sk_buff *skb;
 
        dev->priv_flags &= ~IFF_MACVLAN_PORT;
        netdev_rx_handler_unregister(dev);
@@ -1147,7 +1148,15 @@ static void macvlan_port_destroy(struct net_device *dev)
         * but we need to cancel it and purge left skbs if any.
         */
        cancel_work_sync(&port->bc_work);
-       __skb_queue_purge(&port->bc_queue);
+
+       while ((skb = __skb_dequeue(&port->bc_queue))) {
+               const struct macvlan_dev *src = MACVLAN_SKB_CB(skb)->src;
+
+               if (src)
+                       dev_put(src->dev);
+
+               kfree_skb(skb);
+       }
 
        kfree(port);
 }