netdev - [Patch net] tun: fix a memory leak for tfile->tx

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Message-Id: <20180110000754.13545-1-xiyou.wangcong@gmail.com>
Date:   Tue,  9 Jan 2018 16:07:54 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     dvyukov@...gle.com, Cong Wang <xiyou.wangcong@...il.com>,
        Jason Wang <jasowang@...hat.com>
Subject: [Patch net] tun: fix a memory leak for tfile->tx_array

tfile->tun could be detached before we close the tun fd,
via tun_detach_all(), so it should not be used to check for
tfile->tx_array.

Use the same logic as in tun_attach(), just test !tfile->deatched.

Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Fixes: 1576d9860599 ("tun: switch to use skb array for tx")
Cc: Jason Wang <jasowang@...hat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 drivers/net/tun.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 4f4a842a1c9c..1a1f834440a6 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -613,6 +613,7 @@ static void tun_queue_purge(struct tun_file *tfile)
 
 static void __tun_detach(struct tun_file *tfile, bool clean)
 {
+	bool clean_tx_array = !tfile->detached;
 	struct tun_file *ntfile;
 	struct tun_struct *tun;
 
@@ -657,7 +658,7 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
 			    tun->dev->reg_state == NETREG_REGISTERED)
 				unregister_netdevice(tun->dev);
 		}
-		if (tun)
+		if (clean_tx_array)
 			skb_array_cleanup(&tfile->tx_array);
 		sock_put(&tfile->sk);
 	}
-- 
2.13.0