Commit 302a50bc authored by Steffen Klassert's avatar Steffen Klassert
Browse files

xfrm: Fix potential null pointer dereference in xdst_queue_output 



The net_device might be not set on the skb when we try refcounting.
This leads to a null pointer dereference in xdst_queue_output().
It turned out that the refcount to the net_device is not needed
after all. The dst_entry has a refcount to the net_device before
we queue the skb, so it can't go away. Therefore we can remove the
refcount on queueing to fix the null pointer dereference.

Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent 9c9c9ad5

net/xfrm/xfrm_policy.c

+1 −8
Original line number Diff line number Diff line
@@ -320,11 +320,9 @@ static void xfrm_queue_purge(struct sk_buff_head *list) 
{

	struct sk_buff *skb;



	while ((skb = skb_dequeue(list)) != NULL) {

		dev_put(skb->dev);

	while ((skb = skb_dequeue(list)) != NULL)

		kfree_skb(skb);

}

}



/* Rule must be locked. Release descentant resources, announce

 * entry dead. The rule must be unlinked from lists to the moment.
@@ -1758,7 +1756,6 @@ static void xfrm_policy_queue_process(unsigned long arg) 
	struct sk_buff *skb;

	struct sock *sk;

	struct dst_entry *dst;

	struct net_device *dev;

	struct xfrm_policy *pol = (struct xfrm_policy *)arg;

	struct xfrm_policy_queue *pq = &pol->polq;

	struct flowi fl;
@@ -1805,7 +1802,6 @@ static void xfrm_policy_queue_process(unsigned long arg) 
		dst = xfrm_lookup(xp_net(pol), skb_dst(skb)->path,

				  &fl, skb->sk, 0);

		if (IS_ERR(dst)) {

			dev_put(skb->dev);

			kfree_skb(skb);

			continue;

		}
@@ -1814,9 +1810,7 @@ static void xfrm_policy_queue_process(unsigned long arg) 
		skb_dst_drop(skb);

		skb_dst_set(skb, dst);



		dev = skb->dev;

		err = dst_output(skb);

		dev_put(dev);

	}



	return;
@@ -1839,7 +1833,6 @@ static int xdst_queue_output(struct sk_buff *skb) 
	}



	skb_dst_force(skb);

	dev_hold(skb->dev);



	spin_lock_bh(&pq->hold_queue.lock);

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