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macvlan: Fix potential use-after free for broadcasts

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commit 260916dfb48c374f7840f3b86e69afd3afdb6e96 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Herbert Xu 2016-06-01 11:43:00 +08:00 committed by Greg Kroah-Hartman
parent 69101271ba
commit 26f2a93b7c
1 changed files with 8 additions and 2 deletions
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10
drivers/net/macvlan.c
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@ -305,6 +305,8 @@ static void macvlan_process_broadcast(struct work_struct *w)
rcu_read_unlock();
if (src)
dev_put(src->dev);
kfree_skb(skb);
cond_resched();
@ -312,6 +314,7 @@ static void macvlan_process_broadcast(struct work_struct *w)
}
static void macvlan_broadcast_enqueue(struct macvlan_port *port,
const struct macvlan_dev *src,
struct sk_buff *skb)
{
struct sk_buff *nskb;
@ -321,8 +324,12 @@ static void macvlan_broadcast_enqueue(struct macvlan_port *port,
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;
}
@ -432,8 +439,7 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb)
goto out;
}
MACVLAN_SKB_CB(skb)->src = src;
macvlan_broadcast_enqueue(port, skb);
macvlan_broadcast_enqueue(port, src, skb);
return RX_HANDLER_PASS;
}