netdev - [PATCH] net: usb: usbnet: fix use-after-free in race on workqueue

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Message-Id: <20250625-usbnet-uaf-fix-v1-1-421eb05ae6ea@samsung.com>
Date: Wed, 25 Jun 2025 18:33:48 +0900
From: "Peter GJ. Park" <gyujoon.park@...sung.com>
To: Oliver Neukum <oneukum@...e.com>, Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, "Peter GJ. Park" <gyujoon.park@...sung.com>
Subject: [PATCH] net: usb: usbnet: fix use-after-free in race on workqueue

When usbnet_disconnect() queued while usbnet_probe() processing,
it results to free_netdev before kevent gets to run on workqueue,
thus workqueue does assign_work() with referencing freeed memory address.

For graceful disconnect and to prevent use-after-free of netdev pointer,
the fix adds canceling work and timer those are placed by usbnet_probe()

Signed-off-by: Peter GJ. Park <gyujoon.park@...sung.com>
---
 drivers/net/usb/usbnet.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index c04e715a4c2ade3bc5587b0df71643a25cf88c55..3c5d9ba7fa6660273137c80106746103f84f5a37 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1660,6 +1660,9 @@ void usbnet_disconnect (struct usb_interface *intf)
 	usb_free_urb(dev->interrupt);
 	kfree(dev->padding_pkt);
 
+	timer_delete_sync(&dev->delay);
+	tasklet_kill(&dev->bh);
+	cancel_work_sync(&dev->kevent);
 	free_netdev(net);
 }
 EXPORT_SYMBOL_GPL(usbnet_disconnect);

---
base-commit: 86731a2a651e58953fc949573895f2fa6d456841
change-id: 20250625-usbnet-uaf-fix-9ab85de1b8cf

Best regards,
-- 
Peter GJ. Park <gyujoon.park@...sung.com>