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/nl80211.c b/net/wireless/nl80211.c
index 8808431..353e1a4 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -366,16 +366,26 @@
int result = 0, rem_txq_params = 0;
struct nlattr *nl_txq_params;
- rdev = cfg80211_get_dev_from_info(info);
- if (IS_ERR(rdev))
- return PTR_ERR(rdev);
+ rtnl_lock();
- if (info->attrs[NL80211_ATTR_WIPHY_NAME]) {
+ mutex_lock(&cfg80211_mutex);
+
+ rdev = __cfg80211_drv_from_info(info);
+ if (IS_ERR(rdev)) {
+ result = PTR_ERR(rdev);
+ goto unlock;
+ }
+
+ mutex_lock(&rdev->mtx);
+
+ if (info->attrs[NL80211_ATTR_WIPHY_NAME])
result = cfg80211_dev_rename(
rdev, nla_data(info->attrs[NL80211_ATTR_WIPHY_NAME]));
- if (result)
- goto bad_res;
- }
+
+ mutex_unlock(&cfg80211_mutex);
+
+ if (result)
+ goto bad_res;
if (info->attrs[NL80211_ATTR_WIPHY_TXQ_PARAMS]) {
struct ieee80211_txq_params txq_params;
@@ -471,7 +481,9 @@
bad_res:
- cfg80211_put_dev(rdev);
+ mutex_unlock(&rdev->mtx);
+ unlock:
+ rtnl_unlock();
return result;
}