mac80211: fix a crash triggered by sta disconnect with per-sta VLANs

Reported-by: ranygh@riseup.net
Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/kernel/mac80211/patches/subsys/332-wifi-mac80211-check-clear-fast-rx-for-non-4addr-sta-.patch

@@ -0,0 +1,35 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 16 Mar 2024 08:37:21 +0100
+Subject: [PATCH] wifi: mac80211: check/clear fast rx for non-4addr sta VLAN
+ changes
+
+When moving a station out of a VLAN and deleting the VLAN afterwards, the
+fast_rx entry still holds a pointer to the VLAN's netdev, which can cause
+use-after-free bugs. Fix this by immediately calling ieee80211_check_fast_rx
+after the VLAN change.
+
+Cc: stable@vger.kernel.org
+Reported-by: ranygh@riseup.net
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/cfg.c
++++ b/net/mac80211/cfg.c
+@@ -2184,15 +2184,14 @@ static int ieee80211_change_station(stru
+ 		}
+
+ 		if (sta->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
+-		    sta->sdata->u.vlan.sta) {
+-			ieee80211_clear_fast_rx(sta);
++		    sta->sdata->u.vlan.sta)
+ 			RCU_INIT_POINTER(sta->sdata->u.vlan.sta, NULL);
+-		}
+
+ 		if (test_sta_flag(sta, WLAN_STA_AUTHORIZED))
+ 			ieee80211_vif_dec_num_mcast(sta->sdata);
+
+ 		sta->sdata = vlansdata;
++		ieee80211_check_fast_rx(sta);
+ 		ieee80211_check_fast_xmit(sta);
+
+ 		if (test_sta_flag(sta, WLAN_STA_AUTHORIZED)) {