wifi: mac80211: finish link init before RCU publish

Since the link/conf pointers can be accessed without any
protection other than RCU, make sure the data is actually
set up before publishing the structures.

Fixes: b2e8434 ("wifi: mac80211: set up/tear down client vif links properly")
Link: https://patch.msgid.link/20250624130749.9a308b713c74.I4a80f5eead112a38730939ea591d2e275c721256@changeid
Signed-off-by: Johannes Berg <[email protected]>

Author: jmberg-intel

net/mac80211/link.c

@@ -93,9 +93,6 @@ void ieee80211_link_init(struct ieee80211_sub_if_data *sdata,
 	if (link_id < 0)
 		link_id = 0;
 
-	rcu_assign_pointer(sdata->vif.link_conf[link_id], link_conf);
-	rcu_assign_pointer(sdata->link[link_id], link);
-
 	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
 		struct ieee80211_sub_if_data *ap_bss;
 		struct ieee80211_bss_conf *ap_bss_conf;
@@ -145,6 +142,9 @@ void ieee80211_link_init(struct ieee80211_sub_if_data *sdata,
 
 		ieee80211_link_debugfs_add(link);
 	}
+
+	rcu_assign_pointer(sdata->vif.link_conf[link_id], link_conf);
+	rcu_assign_pointer(sdata->link[link_id], link);
 }
 
 void ieee80211_link_stop(struct ieee80211_link_data *link)