Patch "tun: call dev_get_valid_name() before register_netdevice()" has been added to the 4.13-stable tree

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

tun: call dev_get_valid_name() before register_netdevice()

to the 4.13-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-call-dev_get_valid_name-before-register_netdevice.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Cong Wang <[email protected]>
Date: Fri, 13 Oct 2017 11:58:53 -0700
Subject: tun: call dev_get_valid_name() before register_netdevice()

From: Cong Wang <[email protected]>

[ Upstream commit 0ad646c81b2182f7fa67ec0c8c825e0ee165696d ]

register_netdevice() could fail early when we have an invalid dev name, in which case ->ndo_uninit() is not called. For tun device, this is a problem because a timer etc. are already initialized and it expects ->ndo_uninit() to clean them up.

We could move these initializations into a ->ndo_init() so that register_netdevice() knows better, however this is still complicated due to the logic in tun_detach().

Therefore, I choose to just call dev_get_valid_name() before register_netdevice(), which is quicker and much easier to audit. And for this specific case, it is already enough.

---
 drivers/net/tun.c         |    3 +++
 include/linux/netdevice.h |    3 +++
 net/core/dev.c            |    6 +++---
 3 files changed, 9 insertions(+), 3 deletions(-)

@@ -1813,6 +1813,9 @@ static int tun_set_iff(struct net *net,
 
 		if (!dev)
 			return -ENOMEM;
+		err = dev_get_valid_name(net, dev, name);
+		if (err)
+			goto err_free_dev;
 
 		dev_net_set(dev, net);
 		dev->rtnl_link_ops = &tun_link_ops;

@@ -3702,6 +3702,9 @@ struct net_device *alloc_netdev_mqs(int
 				    unsigned char name_assign_type,
 				    void (*setup)(struct net_device *),
 				    unsigned int txqs, unsigned int rxqs);
+int dev_get_valid_name(struct net *net, struct net_device *dev,
+		       const char *name);
+
 #define alloc_netdev(sizeof_priv, name, name_assign_type, setup) \
 	alloc_netdev_mqs(sizeof_priv, name, name_assign_type, setup, 1, 1)
 

@@ -1146,9 +1146,8 @@ static int dev_alloc_name_ns(struct net
 	return ret;
 }
 
-static int dev_get_valid_name(struct net *net,
-			      struct net_device *dev,
-			      const char *name)
+int dev_get_valid_name(struct net *net, struct net_device *dev,
+		       const char *name)
 {
 	BUG_ON(!net);
 

@@ -1164,6 +1163,7 @@ static int dev_get_valid_name(struct net
 
 	return 0;
 }
+EXPORT_SYMBOL(dev_get_valid_name);
 
 /**
  *	dev_change_name - change name of a device

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/tun-call-dev_get_valid_name-before-register_netdevice.patch queue-4.13/net_sched-avoid-matching-qdisc-with-zero-handle.patch queue-4.13/tun-allow-positive-return-values-on-dev_get_valid_name-call.patch