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Commit 2940bb69 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by John W. Linville
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wireless: Add missing locking to cfg80211_dev_rename 



device_rename only performs useful and race free validity
checking at the optional sysfs level so depending on it
for all of the validity checking in cfg80211_dev_rename
is racy.

Instead implement all of the needed validity checking
and locking in cfg80211_dev_rename.

Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Acked-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 601ae7f2

net/wireless/core.c

+28 −5
Original line number Diff line number Diff line
@@ -143,8 +143,11 @@ void cfg80211_put_dev(struct cfg80211_registered_device *drv) 
int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,

			char *newname)

{

	struct cfg80211_registered_device *drv;

	int idx, taken = -1, result, digits;



	mutex_lock(&cfg80211_drv_mutex);



	/* prohibit calling the thing phy%d when %d is not its number */

	sscanf(newname, PHY_NAME "%d%n", &idx, &taken);

	if (taken == strlen(newname) && idx != rdev->idx) {
@@ -156,14 +159,30 @@ int cfg80211_dev_rename(struct cfg80211_registered_device *rdev, 
		 * deny the name if it is phy<idx> where <idx> is printed

		 * without leading zeroes. taken == strlen(newname) here

		 */

		result = -EINVAL;

		if (taken == strlen(PHY_NAME) + digits)

			return -EINVAL;

			goto out_unlock;

	}



	/* this will check for collisions */



	/* Ignore nop renames */

	result = 0;

	if (strcmp(newname, dev_name(&rdev->wiphy.dev)) == 0)

		goto out_unlock;



	/* Ensure another device does not already have this name. */

	list_for_each_entry(drv, &cfg80211_drv_list, list) {

		result = -EINVAL;

		if (strcmp(newname, dev_name(&drv->wiphy.dev)) == 0)

			goto out_unlock;

	}



	/* this will only check for collisions in sysfs

	 * which is not even always compiled in.

	 */

	result = device_rename(&rdev->wiphy.dev, newname);

	if (result)

		return result;

		goto out_unlock;



	if (!debugfs_rename(rdev->wiphy.debugfsdir->d_parent,

			    rdev->wiphy.debugfsdir,
@@ -172,9 +191,13 @@ int cfg80211_dev_rename(struct cfg80211_registered_device *rdev, 
		printk(KERN_ERR "cfg80211: failed to rename debugfs dir to %s!\n",

		       newname);



	result = 0;

out_unlock:

	mutex_unlock(&cfg80211_drv_mutex);

	if (result == 0)

		nl80211_notify_dev_rename(rdev);



	return 0;

	return result;

}



/* exported functions */