Commit 8ce6cebc authored by Daniel Lezcano's avatar Daniel Lezcano Committed by David S. Miller
Browse files

net-2.6 : V2 - fix dev_get_valid_name 

the commit:

commit d9031024
Author: Octavian Purdila <opurdila@ixiacom.com>
Date:   Wed Nov 18 02:36:59 2009 +0000

    net: device name allocation cleanups

introduced a bug when there is a hash collision making impossible
to rename a device with eth%d. This bug is very hard to reproduce
and appears rarely.

The problem is coming from we don't pass a temporary buffer to
__dev_alloc_name but 'dev->name' which is modified by the function.

A detailed explanation is here:

http://marc.info/?l=linux-netdev&m=127417784011987&w=2



Changelog:
 V2 : replaced strings comparison by pointers comparison

Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@free.fr>
Reviewed-by: default avatarOctavian Purdila <opurdila@ixiacom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a4ed89cb

net/core/dev.c

+12 −8
Original line number Diff line number Diff line
@@ -954,18 +954,22 @@ int dev_alloc_name(struct net_device *dev, const char *name) 
}

EXPORT_SYMBOL(dev_alloc_name);



static int dev_get_valid_name(struct net *net, const char *name, char *buf,

			      bool fmt)

static int dev_get_valid_name(struct net_device *dev, const char *name, bool fmt)

{

	struct net *net;



	BUG_ON(!dev_net(dev));

	net = dev_net(dev);



	if (!dev_valid_name(name))

		return -EINVAL;



	if (fmt && strchr(name, '%'))

		return __dev_alloc_name(net, name, buf);

		return dev_alloc_name(dev, name);

	else if (__dev_get_by_name(net, name))

		return -EEXIST;

	else if (buf != name)

		strlcpy(buf, name, IFNAMSIZ);

	else if (dev->name != name)

		strlcpy(dev->name, name, IFNAMSIZ);



	return 0;

}
@@ -997,7 +1001,7 @@ int dev_change_name(struct net_device *dev, const char *newname) 


	memcpy(oldname, dev->name, IFNAMSIZ);



	err = dev_get_valid_name(net, newname, dev->name, 1);

	err = dev_get_valid_name(dev, newname, 1);

	if (err < 0)

		return err;
@@ -4965,7 +4969,7 @@ int register_netdevice(struct net_device *dev) 
		}

	}



	ret = dev_get_valid_name(net, dev->name, dev->name, 0);

	ret = dev_get_valid_name(dev, dev->name, 0);

	if (ret)

		goto err_uninit;
@@ -5574,7 +5578,7 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char 
		/* We get here if we can't use the current device name */

		if (!pat)

			goto out;

		if (dev_get_valid_name(net, pat, dev->name, 1))

		if (dev_get_valid_name(dev, pat, 1))

			goto out;

	}

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