mac80211: fix setting IEEE80211_KEY_FLAG_RX_MGMT for AP mode keys

BugLink: https://bugs.launchpad.net/bugs/1801893

commit 211710ca upstream.

key->sta is only valid after ieee80211_key_link, which is called later
in this function. Because of that, the IEEE80211_KEY_FLAG_RX_MGMT is
never set when management frame protection is enabled.

Fixes: e548c49e ("mac80211: add key flag for management keys")
Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

net/mac80211/cfg.c

@@ -219,7 +219,7 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
 	case NL80211_IFTYPE_AP:
 	case NL80211_IFTYPE_AP_VLAN:
 		/* Keys without a station are used for TX only */
-		if (key->sta && test_sta_flag(key->sta, WLAN_STA_MFP))
+		if (sta && test_sta_flag(sta, WLAN_STA_MFP))
 			key->conf.flags |= IEEE80211_KEY_FLAG_RX_MGMT;
 		break;
 	case NL80211_IFTYPE_ADHOC: