cfg80211: fix locking in nl80211_set_wiphy
Luis reports that there's a circular locking dependency;
this is because cfg80211_dev_rename() will acquire the
cfg80211_mutex while the device mutex is held, while
this normally is done the other way around. The solution
is to open-code the device-getting in nl80211_set_wiphy
and require holding the mutex around cfg80211_dev_rename
rather than acquiring it within.
Also fix a bug -- rtnl locking is expected by drivers so
we need to provide it.
Reported-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 17fe390..d1f5565 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -87,7 +87,7 @@
}
/* requires cfg80211_mutex to be held! */
-static struct cfg80211_registered_device *
+struct cfg80211_registered_device *
__cfg80211_drv_from_info(struct genl_info *info)
{
int ifindex;
@@ -176,13 +176,14 @@
mutex_unlock(&drv->mtx);
}
+/* requires cfg80211_mutex to be held */
int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
char *newname)
{
struct cfg80211_registered_device *drv;
int wiphy_idx, taken = -1, result, digits;
- mutex_lock(&cfg80211_mutex);
+ assert_cfg80211_lock();
/* prohibit calling the thing phy%d when %d is not its number */
sscanf(newname, PHY_NAME "%d%n", &wiphy_idx, &taken);
@@ -195,30 +196,23 @@
* 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)
- goto out_unlock;
+ return -EINVAL;
}
/* Ignore nop renames */
- result = 0;
if (strcmp(newname, dev_name(&rdev->wiphy.dev)) == 0)
- goto out_unlock;
+ return 0;
/* Ensure another device does not already have this name. */
- list_for_each_entry(drv, &cfg80211_drv_list, list) {
- result = -EINVAL;
+ list_for_each_entry(drv, &cfg80211_drv_list, list)
if (strcmp(newname, dev_name(&drv->wiphy.dev)) == 0)
- goto out_unlock;
- }
+ return -EINVAL;
- /* this will only check for collisions in sysfs
- * which is not even always compiled in.
- */
result = device_rename(&rdev->wiphy.dev, newname);
if (result)
- goto out_unlock;
+ return result;
if (rdev->wiphy.debugfsdir &&
!debugfs_rename(rdev->wiphy.debugfsdir->d_parent,
@@ -228,13 +222,9 @@
printk(KERN_ERR "cfg80211: failed to rename debugfs dir to %s!\n",
newname);
- result = 0;
-out_unlock:
- mutex_unlock(&cfg80211_mutex);
- if (result == 0)
- nl80211_notify_dev_rename(rdev);
+ nl80211_notify_dev_rename(rdev);
- return result;
+ return 0;
}
/* exported functions */