Bluetooth: btmtkuart: fix a memleak in mtk_hci_wmt_sync

bdev->evt_skb will get freed in the normal path and one error path
of mtk_hci_wmt_sync, while the other error paths do not free it,
which may cause a memleak. This bug is suggested by a static analysis
tool, please advise.

Fixes: e0b67035a9 ("Bluetooth: mediatek: update the common setup between MT7622 and other devices")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btmtkuart.c

@@ -158,8 +158,10 @@ static int mtk_hci_wmt_sync(struct hci_dev *hdev,
 	int err;
 
 	hlen = sizeof(*hdr) + wmt_params->dlen;
-	if (hlen > 255)
-		return -EINVAL;
+	if (hlen > 255) {
+		err = -EINVAL;
+		goto err_free_skb;
+	}
 
 	hdr = (struct mtk_wmt_hdr *)&wc;
 	hdr->dir = 1;
@@ -173,7 +175,7 @@ static int mtk_hci_wmt_sync(struct hci_dev *hdev,
 	err = __hci_cmd_send(hdev, 0xfc6f, hlen, &wc);
 	if (err < 0) {
 		clear_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state);
-		return err;
+		goto err_free_skb;
 	}
 
 	/* The vendor specific WMT commands are all answered by a vendor
@@ -190,13 +192,14 @@ static int mtk_hci_wmt_sync(struct hci_dev *hdev,
 	if (err == -EINTR) {
 		bt_dev_err(hdev, "Execution of wmt command interrupted");
 		clear_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state);
-		return err;
+		goto err_free_skb;
 	}
 
 	if (err) {
 		bt_dev_err(hdev, "Execution of wmt command timed out");
 		clear_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state);
-		return -ETIMEDOUT;
+		err = -ETIMEDOUT;
+		goto err_free_skb;
 	}
 
 	/* Parse and handle the return WMT event */