linux-kernel - [PATCH] ath9k: hif_usb: fix memory leak of urbs in ath9k_hif_usb_dealloc_tx

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Date:   Mon, 25 Jul 2022 18:13:59 +0300
From:   Fedor Pchelkin <pchelkin@...ras.ru>
To:     Toke Høiland-Jørgensen <toke@...e.dk>,
        Kalle Valo <kvalo@...nel.org>
Cc:     Fedor Pchelkin <pchelkin@...ras.ru>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Brooke Basile <brookebasile@...il.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Alexey Khoroshilov <khoroshilov@...ras.ru>
Subject: [PATCH] ath9k: hif_usb: fix memory leak of urbs in ath9k_hif_usb_dealloc_tx_urbs()

Syzkaller reports a long-known leak of urbs in
ath9k_hif_usb_dealloc_tx_urbs().

The cause of the leak is that usb_get_urb() is called but usb_free_urb()
(or usb_put_urb()) is not called inside usb_kill_urb() as urb->dev or
urb->ep fields have not been initialized and usb_kill_urb() returns
immediately.

The patch removes trying to kill urbs located in hif_dev->tx.tx_buf
because hif_dev->tx.tx_buf is not supposed to contain urbs which are in
pending state (the pending urbs are stored in hif_dev->tx.tx_pending).
The tx.tx_lock is acquired so there should not be any changes in the list.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 03fb92a432ea ("ath9k: hif_usb: fix race condition between usb_get_urb() and usb_kill_anchored_urbs()")
Signed-off-by: Fedor Pchelkin <pchelkin@...ras.ru>
Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
---
 drivers/net/wireless/ath/ath9k/hif_usb.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 518deb5098a2..2d2cd895a9d4 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -780,14 +780,10 @@ static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)
 	spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
 	list_for_each_entry_safe(tx_buf, tx_buf_tmp,
 				 &hif_dev->tx.tx_buf, list) {
-		usb_get_urb(tx_buf->urb);
-		spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags);
-		usb_kill_urb(tx_buf->urb);
 		list_del(&tx_buf->list);
 		usb_free_urb(tx_buf->urb);
 		kfree(tx_buf->buf);
 		kfree(tx_buf);
-		spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
 	}
 	spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags);
 
-- 
2.25.1