Patch "tun: fix a memory leak for tfile->tx_array" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    tun: fix a memory leak for tfile->tx_array

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tun-fix-a-memory-leak-for-tfile-tx_array.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Sun Jan 28 17:37:09 CET 2018
From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Mon, 15 Jan 2018 11:37:29 -0800
Subject: tun: fix a memory leak for tfile->tx_array

From: Cong Wang <xiyou.wangcong@gmail.com>


[ Upstream commit 4df0bfc79904b7169dc77dcce44598b1545721f9 ]

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.

As Jason suggested, we probably have to clean it up
unconditionally both in __tun_deatch() and tun_detach_all(),
but this requires to check if it is initialized or not.
Currently skb_array_cleanup() doesn't have such a check,
so I check it in the caller and introduce a helper function,
it is a bit ugly but we can always improve it in net-next.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Fixes: 1576d9860599 ("tun: switch to use skb array for tx")
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/tun.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -525,6 +525,14 @@ static void tun_queue_purge(struct tun_f
 	skb_queue_purge(&tfile->sk.sk_error_queue);
 }
 
+static void tun_cleanup_tx_array(struct tun_file *tfile)
+{
+	if (tfile->tx_array.ring.queue) {
+		skb_array_cleanup(&tfile->tx_array);
+		memset(&tfile->tx_array, 0, sizeof(tfile->tx_array));
+	}
+}
+
 static void __tun_detach(struct tun_file *tfile, bool clean)
 {
 	struct tun_file *ntfile;
@@ -566,8 +574,7 @@ static void __tun_detach(struct tun_file
 			    tun->dev->reg_state == NETREG_REGISTERED)
 				unregister_netdevice(tun->dev);
 		}
-		if (tun)
-			skb_array_cleanup(&tfile->tx_array);
+		tun_cleanup_tx_array(tfile);
 		sock_put(&tfile->sk);
 	}
 }
@@ -606,11 +613,13 @@ static void tun_detach_all(struct net_de
 		/* Drop read queue */
 		tun_queue_purge(tfile);
 		sock_put(&tfile->sk);
+		tun_cleanup_tx_array(tfile);
 	}
 	list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
 		tun_enable_queue(tfile);
 		tun_queue_purge(tfile);
 		sock_put(&tfile->sk);
+		tun_cleanup_tx_array(tfile);
 	}
 	BUG_ON(tun->numdisabled != 0);
 
@@ -2363,6 +2372,8 @@ static int tun_chr_open(struct inode *in
 
 	sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);
 
+	memset(&tfile->tx_array, 0, sizeof(tfile->tx_array));
+
 	return 0;
 }
 


Patches currently in stable-queue which might be from xiyou.wangcong@gmail.com are

queue-4.9/tipc-fix-a-memory-leak-in-tipc_nl_node_get_link.patch
queue-4.9/tun-fix-a-memory-leak-for-tfile-tx_array.patch