macvlan: Fix potential use-after free for broadcasts
When we postpone a broadcast packet we save the source port in
the skb if it is local. However, the source port can disappear
before we get a chance to process the packet.
This patch fixes this by holding a ref count on the netdev.
It also delays the skb->cb modification until after we allocate
the new skb as you should not modify shared skbs.
Fixes: 412ca1550cbe ("macvlan: Move broadcasts into a work queue")
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 cb01023..a71fa59 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -305,11 +305,14 @@
rcu_read_unlock();
+ if (src)
+ dev_put(src->dev);
kfree_skb(skb);
}
}
static void macvlan_broadcast_enqueue(struct macvlan_port *port,
+ const struct macvlan_dev *src,
struct sk_buff *skb)
{
struct sk_buff *nskb;
@@ -319,8 +322,12 @@
if (!nskb)
goto err;
+ MACVLAN_SKB_CB(nskb)->src = src;
+
spin_lock(&port->bc_queue.lock);
if (skb_queue_len(&port->bc_queue) < MACVLAN_BC_QUEUE_LEN) {
+ if (src)
+ dev_hold(src->dev);
__skb_queue_tail(&port->bc_queue, nskb);
err = 0;
}
@@ -429,8 +436,7 @@
goto out;
}
- MACVLAN_SKB_CB(skb)->src = src;
- macvlan_broadcast_enqueue(port, skb);
+ macvlan_broadcast_enqueue(port, src, skb);
return RX_HANDLER_PASS;
}