netdev - [PATCH net] macvtap: fix use after free for skb

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Date:	Thu, 11 Aug 2016 18:15:56 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	davem@...emloft.net
Cc:	borntraeger@...ibm.com, cornelia.huck@...ibm.com, mst@...hat.com,
	Jason Wang <jasowang@...hat.com>
Subject: [PATCH net] macvtap: fix use after free for skb_array during release

We've clean skb_array in macvtap_put_queue() but still try to pop from
it during macvtap_sock_destruct(). Fix this use after free by moving
the skb array cleanup to macvtap_sock_destruct() instead.

Fixes: 362899b8725b ("macvtap: switch to use skb array")
Reported-by: Cornelia Huck <cornelia.huck@...ibm.com>
Tested-by: Cornelia Huck <cornelia.huck@...ibm.com>
Signed-off-by: Jason Wang <jasowang@...hat.com>
---
 drivers/net/macvtap.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index a38c0da..070e329 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -275,7 +275,6 @@ static void macvtap_put_queue(struct macvtap_queue *q)
 	rtnl_unlock();
 
 	synchronize_rcu();
-	skb_array_cleanup(&q->skb_array);
 	sock_put(&q->sk);
 }
 
@@ -533,10 +532,8 @@ static void macvtap_sock_write_space(struct sock *sk)
 static void macvtap_sock_destruct(struct sock *sk)
 {
 	struct macvtap_queue *q = container_of(sk, struct macvtap_queue, sk);
-	struct sk_buff *skb;
 
-	while ((skb = skb_array_consume(&q->skb_array)) != NULL)
-		kfree_skb(skb);
+	skb_array_cleanup(&q->skb_array);
 }
 
 static int macvtap_open(struct inode *inode, struct file *file)
-- 
2.7.4