linux-kernel - Memory leak in ath9k_hif_usb_dealloc_tx

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Date:   Tue, 30 Mar 2021 22:36:52 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     brookebasile@...il.com
Cc:     ath9k-devel@....qualcomm.com, davem@...emloft.net,
        gregkh@...uxfoundation.org, kuba@...nel.org, kvalo@...eaurora.org,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        syzbot+89bd486af9427a9fc605@...kaller.appspotmail.com,
        syzkaller-bugs@...glegroups.com
Subject: Memory leak in ath9k_hif_usb_dealloc_tx_urbs()

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