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* [PATCH net] tuntap: fix use after free during release
@ 2018-05-16 12:39 Jason Wang
  2018-05-16 18:53 ` David Miller
  0 siblings, 1 reply; 2+ messages in thread
From: Jason Wang @ 2018-05-16 12:39 UTC (permalink / raw)
  To: netdev, linux-kernel; +Cc: xiyou.wangcong, avagin, mst, Jason Wang

After commit b196d88aba8a ("tun: fix use after free for ptr_ring") we
need clean up tx ring during release(). But unfortunately, it tries to
do the cleanup blindly after socket were destroyed which will lead
another use-after-free. Fix this by doing the cleanup before dropping
the last reference of the socket in __tun_detach().

Reported-by: Andrei Vagin <avagin@virtuozzo.com>
Acked-by: Andrei Vagin <avagin@virtuozzo.com>
Fixes: b196d88aba8a ("tun: fix use after free for ptr_ring")
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/tun.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 9fbbb32..d45ac37 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -729,6 +729,7 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
 		}
 		if (tun)
 			xdp_rxq_info_unreg(&tfile->xdp_rxq);
+		ptr_ring_cleanup(&tfile->tx_ring, tun_ptr_free);
 		sock_put(&tfile->sk);
 	}
 }
@@ -3245,7 +3246,6 @@ static int tun_chr_close(struct inode *inode, struct file *file)
 	struct tun_file *tfile = file->private_data;
 
 	tun_detach(tfile, true);
-	ptr_ring_cleanup(&tfile->tx_ring, tun_ptr_free);
 
 	return 0;
 }
-- 
2.7.4

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH net] tuntap: fix use after free during release
  2018-05-16 12:39 [PATCH net] tuntap: fix use after free during release Jason Wang
@ 2018-05-16 18:53 ` David Miller
  0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2018-05-16 18:53 UTC (permalink / raw)
  To: jasowang; +Cc: netdev, linux-kernel, xiyou.wangcong, avagin, mst

From: Jason Wang <jasowang@redhat.com>
Date: Wed, 16 May 2018 20:39:33 +0800

> After commit b196d88aba8a ("tun: fix use after free for ptr_ring") we
> need clean up tx ring during release(). But unfortunately, it tries to
> do the cleanup blindly after socket were destroyed which will lead
> another use-after-free. Fix this by doing the cleanup before dropping
> the last reference of the socket in __tun_detach().
> 
> Reported-by: Andrei Vagin <avagin@virtuozzo.com>
> Acked-by: Andrei Vagin <avagin@virtuozzo.com>
> Fixes: b196d88aba8a ("tun: fix use after free for ptr_ring")
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Applied and queued up for -stable.

^ permalink raw reply	[flat|nested] 2+ messages in thread

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