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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: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
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@ -143,8 +143,11 @@ void cfg80211_put_dev(struct cfg80211_registered_device *drv)
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int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
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char *newname)
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{
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struct cfg80211_registered_device *drv;
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int idx, taken = -1, result, digits;
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mutex_lock(&cfg80211_drv_mutex);
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/* prohibit calling the thing phy%d when %d is not its number */
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sscanf(newname, PHY_NAME "%d%n", &idx, &taken);
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if (taken == strlen(newname) && idx != rdev->idx) {
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@ -156,14 +159,30 @@ int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
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* deny the name if it is phy<idx> where <idx> is printed
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* without leading zeroes. taken == strlen(newname) here
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*/
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result = -EINVAL;
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if (taken == strlen(PHY_NAME) + digits)
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return -EINVAL;
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goto out_unlock;
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}
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/* this will check for collisions */
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/* Ignore nop renames */
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result = 0;
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if (strcmp(newname, dev_name(&rdev->wiphy.dev)) == 0)
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goto out_unlock;
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/* Ensure another device does not already have this name. */
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list_for_each_entry(drv, &cfg80211_drv_list, list) {
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result = -EINVAL;
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if (strcmp(newname, dev_name(&drv->wiphy.dev)) == 0)
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goto out_unlock;
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}
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/* this will only check for collisions in sysfs
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* which is not even always compiled in.
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*/
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result = device_rename(&rdev->wiphy.dev, newname);
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if (result)
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return result;
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goto out_unlock;
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if (!debugfs_rename(rdev->wiphy.debugfsdir->d_parent,
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rdev->wiphy.debugfsdir,
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@ -172,9 +191,13 @@ int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
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printk(KERN_ERR "cfg80211: failed to rename debugfs dir to %s!\n",
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newname);
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nl80211_notify_dev_rename(rdev);
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result = 0;
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out_unlock:
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mutex_unlock(&cfg80211_drv_mutex);
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if (result == 0)
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nl80211_notify_dev_rename(rdev);
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return 0;
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return result;
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}
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/* exported functions */
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