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: Steffen Klassert <steffen.klassert@secunet.com>
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index e52cab3..f77c371 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -320,10 +320,8 @@
{
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
@@ -1758,7 +1756,6 @@
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 @@
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 @@
skb_dst_drop(skb);
skb_dst_set(skb, dst);
- dev = skb->dev;
err = dst_output(skb);
- dev_put(dev);
}
return;
@@ -1839,7 +1833,6 @@
}
skb_dst_force(skb);
- dev_hold(skb->dev);
spin_lock_bh(&pq->hold_queue.lock);