[ 3.5.y.z extended stable ] Patch "dlci: acquire rtnl_lock before calling __dev_get_by_name()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    dlci: acquire rtnl_lock before calling __dev_get_by_name()

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 25f27ae02ea29119814b62f1ae87476132cea780 Mon Sep 17 00:00:00 2001
From: Zefan Li <lizefan at huawei.com>
Date: Wed, 26 Jun 2013 15:29:54 +0800
Subject: [PATCH] dlci: acquire rtnl_lock before calling __dev_get_by_name()

commit 11eb2645cbf38a08ae491bf6c602eea900ec0bb5 upstream.

Otherwise the net device returned can be freed at anytime.

Signed-off-by: Li Zefan <lizefan at huawei.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/wan/dlci.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wan/dlci.c b/drivers/net/wan/dlci.c
index 147614e..1f6e053 100644
--- a/drivers/net/wan/dlci.c
+++ b/drivers/net/wan/dlci.c
@@ -385,20 +385,24 @@ static int dlci_del(struct dlci_add *dlci)
 	struct net_device	*master, *slave;
 	int			err;

+	rtnl_lock();
+
 	/* validate slave device */
 	master = __dev_get_by_name(&init_net, dlci->devname);
-	if (!master)
-		return -ENODEV;
+	if (!master) {
+		err = -ENODEV;
+		goto out;
+	}

 	if (netif_running(master)) {
-		return -EBUSY;
+		err = -EBUSY;
+		goto out;
 	}

 	dlp = netdev_priv(master);
 	slave = dlp->slave;
 	flp = netdev_priv(slave);

-	rtnl_lock();
 	err = (*flp->deassoc)(slave, master);
 	if (!err) {
 		list_del(&dlp->list);
@@ -407,8 +411,8 @@ static int dlci_del(struct dlci_add *dlci)

 		dev_put(slave);
 	}
+out:
 	rtnl_unlock();
-
 	return err;
 }

--
1.8.1.2