I managed to get a device vt6656 (USB WiFi adapter). The device works OK when the computer is started and driver loaded. When the WLAN is disabled the system freezes often. I am using ubuntu 20.04 with kernel 5.17.0-rc1 x86_64 branch: staging-testing After some tries I found out that it is a function in vnt_stop() main_usb.c with the following line that is causing this. usb_kill_urb(priv→interrupt_urb); But this memory is after this line still in use. Digging deeper I found that the usb_submit_urb() function (in usbpipe.c vnt_start_interrupt_urb_complete) is called after the usb_kill_urb() is executed. So I tied the execution of the usb_submit_urb() to a flag called DEVICE_FLAGS_DISCONNECTED. After that no crashes were observed. So here my questions: - Is this the right place to fix? - Do I need to log a bug report before a patch? Here a patch proposal: From d403ed1a1c2483a3a8b44e96c12edbfa2a53d356 Mon Sep 17 00:00:00 2001 From: Philipp Hortmann <philipp.g.hortmann@gmail.com> Date: Wed, 2 Feb 2022 20:15:04 +0100 Subject: [PATCH] staging: vt6656: Fix crash when WLAN is turned off To: Forest Bond <forest@alittletooquiet.net>,Greg Kroah-Hartman <gregkh@linuxfoundation.org>,linux-staging@lists.linux.dev,linux-kernel@vger.kernel.org Stop submitting urbs before calling usb_kill_urb() and usb_free_urb(). Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> --- drivers/staging/vt6656/usbpipe.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/staging/vt6656/usbpipe.c b/drivers/staging/vt6656/usbpipe.c index 7f45734390f6..d505b4b69ba4 100644 --- a/drivers/staging/vt6656/usbpipe.c +++ b/drivers/staging/vt6656/usbpipe.c @@ -230,7 +230,9 @@ static void vnt_start_interrupt_urb_complete(struct urb *urb) else vnt_int_process_data(priv); - status = usb_submit_urb(priv->interrupt_urb, GFP_ATOMIC); + if (!test_bit(DEVICE_FLAGS_DISCONNECTED, &priv->flags)) + status = usb_submit_urb(priv->interrupt_urb, GFP_ATOMIC); + if (status) dev_dbg(&priv->usb->dev, "Submit int URB failed %d\n", status); } -- 2.25.1