mt76: fix key pointer overwrite in mt7921s_write_txwi/mt7663_usb_sdio_write_txwi

Fix pointer overwrite in mt7921s_tx_prepare_skb and
mt7663_usb_sdio_tx_prepare_skb routines since in
commit '2a9e9857 ("mt76: fix possible pktid leak")
mt76_tx_status_skb_add() has been moved out of
mt7921s_write_txwi()/mt7663_usb_sdio_write_txwi() overwriting
hw key pointer in ieee80211_tx_info structure. Fix the issue saving
key pointer before running mt76_tx_status_skb_add().

Fixes: 2a9e9857 ("mt76: fix possible pktid leak")
Tested-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/eba40c84b6d114f618e2ae486cc6d0f2e9272cf9.1638193069.git.lorenzo@kernel.org

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

@@ -43,13 +43,11 @@ EXPORT_SYMBOL_GPL(mt7663_usb_sdio_reg_map);
 static void
 mt7663_usb_sdio_write_txwi(struct mt7615_dev *dev, struct mt76_wcid *wcid,
 			   enum mt76_txq_id qid, struct ieee80211_sta *sta,
-			   int pid, struct sk_buff *skb)
+			   struct ieee80211_key_conf *key, int pid,
+			   struct sk_buff *skb)
 {
-	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-	struct ieee80211_key_conf *key = info->control.hw_key;
-	__le32 *txwi;
+	__le32 *txwi = (__le32 *)(skb->data - MT_USB_TXD_SIZE);
 
-	txwi = (__le32 *)(skb->data - MT_USB_TXD_SIZE);
 	memset(txwi, 0, MT_USB_TXD_SIZE);
 	mt7615_mac_write_txwi(dev, txwi, skb, wcid, sta, pid, key, false);
 	skb_push(skb, MT_USB_TXD_SIZE);
@@ -188,6 +186,7 @@ int mt7663_usb_sdio_tx_prepare_skb(struct mt76_dev *mdev, void *txwi_ptr,
 	struct mt7615_dev *dev = container_of(mdev, struct mt7615_dev, mt76);
 	struct sk_buff *skb = tx_info->skb;
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+	struct ieee80211_key_conf *key = info->control.hw_key;
 	struct mt7615_sta *msta;
 	int pad, err, pktid;
 
@@ -205,7 +204,7 @@ int mt7663_usb_sdio_tx_prepare_skb(struct mt76_dev *mdev, void *txwi_ptr,
 	}
 
 	pktid = mt76_tx_status_skb_add(&dev->mt76, wcid, skb);
-	mt7663_usb_sdio_write_txwi(dev, wcid, qid, sta, pktid, skb);
+	mt7663_usb_sdio_write_txwi(dev, wcid, qid, sta, key, pktid, skb);
 	if (mt76_is_usb(mdev)) {
 		u32 len = skb->len;
 

drivers/net/wireless/mediatek/mt76/mt7921/sdio_mac.c

@@ -142,13 +142,11 @@ int mt7921s_mac_reset(struct mt7921_dev *dev)
 static void
 mt7921s_write_txwi(struct mt7921_dev *dev, struct mt76_wcid *wcid,
 		   enum mt76_txq_id qid, struct ieee80211_sta *sta,
-		   int pid, struct sk_buff *skb)
+		   struct ieee80211_key_conf *key, int pid,
+		   struct sk_buff *skb)
 {
-	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-	struct ieee80211_key_conf *key = info->control.hw_key;
-	__le32 *txwi;
+	__le32 *txwi = (__le32 *)(skb->data - MT_SDIO_TXD_SIZE);
 
-	txwi = (__le32 *)(skb->data - MT_SDIO_TXD_SIZE);
 	memset(txwi, 0, MT_SDIO_TXD_SIZE);
 	mt7921_mac_write_txwi(dev, txwi, skb, wcid, key, pid, false);
 	skb_push(skb, MT_SDIO_TXD_SIZE);
@@ -161,6 +159,7 @@ int mt7921s_tx_prepare_skb(struct mt76_dev *mdev, void *txwi_ptr,
 {
 	struct mt7921_dev *dev = container_of(mdev, struct mt7921_dev, mt76);
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx_info->skb);
+	struct ieee80211_key_conf *key = info->control.hw_key;
 	struct sk_buff *skb = tx_info->skb;
 	int err, pad, pktid;
 
@@ -180,7 +179,7 @@ int mt7921s_tx_prepare_skb(struct mt76_dev *mdev, void *txwi_ptr,
 	}
 
 	pktid = mt76_tx_status_skb_add(&dev->mt76, wcid, skb);
-	mt7921s_write_txwi(dev, wcid, qid, sta, pktid, skb);
+	mt7921s_write_txwi(dev, wcid, qid, sta, key, pktid, skb);
 
 	mt7921_skb_add_sdio_hdr(skb, MT7921_SDIO_DATA);
 	pad = round_up(skb->len, 4) - skb->len;