[net] tuntap: fix use after free during release

Message ID 1526474373-16685-1-git-send-email-jasowang@redhat.com
State Accepted
Delegated to: David Miller
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Series
  • [net] tuntap: fix use after free during release
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Commit Message

Jason Wang May 16, 2018, 12:39 p.m.
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(-)

Comments

David Miller May 16, 2018, 6:53 p.m. | #1
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.

Patch

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;
 }