macvlan: fix a race on port dismantle and possible skb leaks

[ Upstream commit fe0ca7328d03d36aafecebb3af650e1bb2841c20 ]

We need to cancel the work queue after rcu grace period,
otherwise it can be rescheduled by incoming packets.

We need to purge queue if some skbs are still in it.

We can use __skb_queue_head_init() variant in
macvlan_process_broadcast()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 412ca1550cbec ("macvlan: Move broadcasts into a work queue")
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 726edabff26b710d06b622782a71092430b184b4..5f17ad02917ca3d48557866b5a3cd451ed415ee9 100644 (file)
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -201,7 +201,7 @@ static void macvlan_process_broadcast(struct work_struct *w)
        struct sk_buff *skb;
        struct sk_buff_head list;
 
-       skb_queue_head_init(&list);
+       __skb_queue_head_init(&list);
 
        spin_lock_bh(&port->bc_queue.lock);
        skb_queue_splice_tail_init(&port->bc_queue, &list);
@@ -941,9 +941,15 @@ static void macvlan_port_destroy(struct net_device *dev)
 {
        struct macvlan_port *port = macvlan_port_get_rtnl(dev);
 
-       cancel_work_sync(&port->bc_work);
        dev->priv_flags &= ~IFF_MACVLAN_PORT;
        netdev_rx_handler_unregister(dev);
+
+       /* After this point, no packet can schedule bc_work anymore,
+        * but we need to cancel it and purge left skbs if any.
+        */
+       cancel_work_sync(&port->bc_work);
+       __skb_queue_purge(&port->bc_queue);
+
        kfree_rcu(port, rcu);
 }