wifi: mac80211: check key taint for beacon protection

This will likely never happen, but for completeness check
the key taint flag before using a key for beacon protection.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230301115906.cf2c3fee6f1f.I2f19b3e04e31c99bed3c9dc71935bf513b2cd177@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/tx.c

@@ -5115,6 +5115,12 @@ static int ieee80211_beacon_protect(struct sk_buff *skb,
 	tx.key = rcu_dereference(link->default_beacon_key);
 	if (!tx.key)
 		return 0;
+
+	if (unlikely(tx.key->flags & KEY_FLAG_TAINTED)) {
+		tx.key = NULL;
+		return -EINVAL;
+	}
+
 	tx.local = local;
 	tx.sdata = sdata;
 	__skb_queue_head_init(&tx.skbs);