wifi: mac80211: reject address change while connecting

While connecting, the MAC address can already no longer be
changed. The change is already rejected if netif_carrier_ok(),
but of course that's not true yet while connecting. Check for
auth_data or assoc_data, so the MAC address cannot be changed.

Also more comprehensively check that there are no stations on
the interface being changed - if any peer station is added it
will know about our address already, so we cannot change it.

Cc: stable@vger.kernel.org
Fixes: 3c06e91b40 ("wifi: mac80211: Support POWERED_ADDR_CHANGE feature")
Link: https://patch.msgid.link/20251105154119.f9f6c1df81bb.I9bb3760ede650fb96588be0d09a5a7bdec21b217@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/iface.c

@@ -223,6 +223,10 @@ static int ieee80211_can_powered_addr_change(struct ieee80211_sub_if_data *sdata
 	if (netif_carrier_ok(sdata->dev))
 		return -EBUSY;
 
+	/* if any stations are set known (so they know this vif too), reject */
+	if (sta_info_get_by_idx(sdata, 0))
+		return -EBUSY;
+
 	/* First check no ROC work is happening on this iface */
 	list_for_each_entry(roc, &local->roc_list, list) {
 		if (roc->sdata != sdata)
@@ -242,12 +246,16 @@ static int ieee80211_can_powered_addr_change(struct ieee80211_sub_if_data *sdata
 			ret = -EBUSY;
 	}
 
+	/*
+	 * More interface types could be added here but changing the
+	 * address while powered makes the most sense in client modes.
+	 */
 	switch (sdata->vif.type) {
 	case NL80211_IFTYPE_STATION:
 	case NL80211_IFTYPE_P2P_CLIENT:
-		/* More interface types could be added here but changing the
-		 * address while powered makes the most sense in client modes.
-		 */
+		/* refuse while connecting */
+		if (sdata->u.mgd.auth_data || sdata->u.mgd.assoc_data)
+			return -EBUSY;
 		break;
 	default:
 		ret = -EOPNOTSUPP;