wireless: Protect regdomain change by mutex

Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/reg.c

@@ -1830,6 +1830,7 @@ static void restore_custom_reg_settings(struct wiphy *wiphy)
 static void restore_regulatory_settings(bool reset_user)
 {
 	char alpha2[2];
+	char world_alpha2[2];
 	struct reg_beacon *reg_beacon, *btmp;
 	struct regulatory_request *reg_request, *tmp;
 	LIST_HEAD(tmp_reg_req_list);
@@ -1881,6 +1882,8 @@ static void restore_regulatory_settings(bool reset_user)
 
 	/* First restore to the basic regulatory settings */
 	cfg80211_regdomain = cfg80211_world_regdom;
+	world_alpha2[0] = cfg80211_regdomain->alpha2[0];
+	world_alpha2[1] = cfg80211_regdomain->alpha2[1];
 
 	list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
 		if (rdev->wiphy.flags & WIPHY_FLAG_CUSTOM_REGULATORY)
@@ -1890,7 +1893,7 @@ static void restore_regulatory_settings(bool reset_user)
 	mutex_unlock(&reg_mutex);
 	mutex_unlock(&cfg80211_mutex);
 
-	regulatory_hint_core(cfg80211_regdomain->alpha2);
+	regulatory_hint_core(world_alpha2);
 
 	/*
 	 * This restores the ieee80211_regdom module parameter