Memory leak in ath9k_hif_usb_dealloc_tx_urbs()

[Pavel Skripkin]

Hi!

I did some debugging on this
https://syzkaller.appspot.com/bug?id=3ea507fb3c47426497b52bd82b8ef0dd5b6cc7ee
and, I believe, I recognized the problem. The problem appears in case of
ath9k_htc_hw_init() fail. In case of this fail all tx_buf->urb krefs will be
initialized to 1, but in free function:

static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)

....

static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)
{
    ...
        list_for_each_entry_safe(tx_buf, tx_buf_tmp,
                                 &hif_dev->tx.tx_buf, list) {
                usb_get_urb(tx_buf->urb);
                ...
                usb_free_urb(tx_buf->urb);
                ...
                }

Krefs are incremented and then decremented, that means urbs won't be freed.
I found your patch and I can't properly understand why You added 
usb_get_urb(tx_buf->urb).
Can You explain please, I believe this will help me or somebody to fix this 
ussue :)

With regards,
Pavel Skripkin