mt76: mt7615: fix skb use-after-free on mac reset

When clearing all existing pending tx slots, mt76_tx_complete_skb needs to
be used to free the skbs, to ensure that they are cleared from the status
list as well.

Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7615/mac.c

@@ -1497,32 +1497,41 @@ static void mt7615_mac_add_txs(struct mt7615_dev *dev, void *data)
 }
 
 static void
-mt7615_mac_tx_free_token(struct mt7615_dev *dev, u16 token)
+mt7615_txwi_free(struct mt7615_dev *dev, struct mt76_txwi_cache *txwi)
 {
 	struct mt76_dev *mdev = &dev->mt76;
-	struct mt76_txwi_cache *txwi;
 	__le32 *txwi_data;
 	u32 val;
 	u8 wcid;
 
-	trace_mac_tx_free(dev, token);
-	txwi = mt76_token_put(mdev, token);
-	if (!txwi)
-		return;
+	mt7615_txp_skb_unmap(mdev, txwi);
+	if (!txwi->skb)
+		goto out;
 
 	txwi_data = (__le32 *)mt76_get_txwi_ptr(mdev, txwi);
 	val = le32_to_cpu(txwi_data[1]);
 	wcid = FIELD_GET(MT_TXD1_WLAN_IDX, val);
-
-	mt7615_txp_skb_unmap(mdev, txwi);
-	if (txwi->skb) {
 	mt76_tx_complete_skb(mdev, wcid, txwi->skb);
-		txwi->skb = NULL;
-	}
 
+out:
+	txwi->skb = NULL;
 	mt76_put_txwi(mdev, txwi);
 }
 
+static void
+mt7615_mac_tx_free_token(struct mt7615_dev *dev, u16 token)
+{
+	struct mt76_dev *mdev = &dev->mt76;
+	struct mt76_txwi_cache *txwi;
+
+	trace_mac_tx_free(dev, token);
+	txwi = mt76_token_put(mdev, token);
+	if (!txwi)
+		return;
+
+	mt7615_txwi_free(dev, txwi);
+}
+
 static void mt7615_mac_tx_free(struct mt7615_dev *dev, struct sk_buff *skb)
 {
 	struct mt7615_tx_free *free = (struct mt7615_tx_free *)skb->data;
@@ -2029,16 +2038,8 @@ void mt7615_tx_token_put(struct mt7615_dev *dev)
 	int id;
 
 	spin_lock_bh(&dev->mt76.token_lock);
-	idr_for_each_entry(&dev->mt76.token, txwi, id) {
-		mt7615_txp_skb_unmap(&dev->mt76, txwi);
-		if (txwi->skb) {
-			struct ieee80211_hw *hw;
-
-			hw = mt76_tx_status_get_hw(&dev->mt76, txwi->skb);
-			ieee80211_free_txskb(hw, txwi->skb);
-		}
-		mt76_put_txwi(&dev->mt76, txwi);
-	}
+	idr_for_each_entry(&dev->mt76.token, txwi, id)
+		mt7615_txwi_free(dev, txwi);
 	spin_unlock_bh(&dev->mt76.token_lock);
 	idr_destroy(&dev->mt76.token);
 }