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From: Brooke Basile <brookebasile@gmail.com>
To: kvalo@codeaurora.org, davem@davemloft.net, kuba@kernel.org
Cc: gregkh@linuxfoundation.org, linux-wireless@vger.kernel.org,
	linux-kernel@vger.kernel.org, ath9k-devel@qca.qualcomm.com,
	syzkaller-bugs@googlegroups.com,
	Brooke Basile <brookebasile@gmail.com>,
	syzbot+89bd486af9427a9fc605@syzkaller.appspotmail.com
Subject: [PATCH] wireless: ath9k: hif_usb: fix race condition between usb_get_urb() and usb_kill_anchored_urbs()
Date: Fri, 11 Sep 2020 03:14:27 -0400	[thread overview]
Message-ID: <20200911071427.32354-1-brookebasile@gmail.com> (raw)

Calls to usb_kill_anchored_urbs() after usb_kill_urb() on multiprocessor
systems create a race condition in which usb_kill_anchored_urbs() deallocates
the URB before the completer callback is called in usb_kill_urb(), resulting
in a use-after-free.
To fix this, add proper lock protection to usb_kill_urb() calls that can
possibly run concurrently with usb_kill_anchored_urbs().

Reported-by: syzbot+89bd486af9427a9fc605@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=cabffad18eb74197f84871802fd2c5117b61febf
Signed-off-by: Brooke Basile <brookebasile@gmail.com>
---
 drivers/net/wireless/ath/ath9k/hif_usb.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 3f563e02d17d..2ed98aaed6fb 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -449,10 +449,19 @@ static void hif_usb_stop(void *hif_handle)
 	spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags);

 	/* The pending URBs have to be canceled. */
+	spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
 	list_for_each_entry_safe(tx_buf, tx_buf_tmp,
 				 &hif_dev->tx.tx_pending, 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);

 	usb_kill_anchored_urbs(&hif_dev->mgmt_submitted);
 }
@@ -762,27 +771,37 @@ static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)
 	struct tx_buf *tx_buf = NULL, *tx_buf_tmp = NULL;
 	unsigned long flags;

+	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);

 	spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
 	hif_dev->tx.flags |= HIF_USB_TX_FLUSH;
 	spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags);

+	spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
 	list_for_each_entry_safe(tx_buf, tx_buf_tmp,
 				 &hif_dev->tx.tx_pending, 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);

 	usb_kill_anchored_urbs(&hif_dev->mgmt_submitted);
 }
--
2.28.0


             reply	other threads:[~2020-09-11  7:14 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-11  7:14 Brooke Basile [this message]
2020-09-20  2:03 ` [PATCH] wireless: ath9k: hif_usb: fix race condition between usb_get_urb() and usb_kill_anchored_urbs() Brooke Basile
2020-09-21 13:05 ` Kalle Valo
     [not found] ` <20200921130559.005D8C43382@smtp.codeaurora.org>
2020-09-21 23:04   ` Brooke Basile
2021-03-30 19:36 ` Memory leak in ath9k_hif_usb_dealloc_tx_urbs() Pavel Skripkin
2021-03-31  6:28   ` Greg KH
2021-04-27 11:35     ` Atul Gopinathan
2021-04-27 11:50       ` Greg KH
2021-04-27 12:04       ` Pavel Skripkin
2021-04-27 12:29         ` Pavel Skripkin
2021-04-27 13:01           ` Atul Gopinathan

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