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SubjectRe: [PATCH RESEND] usbip: vudc: Fix use after free bug in vudc_remove due to race condition
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On 3/16/23 11:48, Zheng Wang wrote:
> In vudc_probe, it calls init_vudc_hw, which bound &udc->timer with v_timer.
>
> When it calls usbip_sockfd_store, it will call v_start_timer to start the
> timer work.
>
> When we call vudc_remove to remove the driver, theremay be a sequence as
> follows:
>
> Fix it by shutdown the timer work before cleanup in vudc_remove.
>

Send me v2 for this patch with adding details on how you found this problem
to this commit log.

> Note that removing a driver is a root-only operation, and should never
> happen.
>
> CPU0 CPU1
>
> |v_timer
> vudc_remove |
> kfree(udc); |
> //free shost |
> |udc->gadget
> |//use
>
> Fixes: b6a0ca111867 ("usbip: vudc: Add UDC specific ops")
> Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> ---
> drivers/usb/usbip/vudc_dev.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c
> index 2bc428f2e261..33d0991755bb 100644
> --- a/drivers/usb/usbip/vudc_dev.c
> +++ b/drivers/usb/usbip/vudc_dev.c
> @@ -633,6 +633,7 @@ int vudc_remove(struct platform_device *pdev)
> {
> struct vudc *udc = platform_get_drvdata(pdev);
>
> + timer_shutdown_sync(&udc->timer);
> usb_del_gadget_udc(&udc->gadget);
> cleanup_vudc_hw(udc);
> kfree(udc);

thanks,
-- Shuah

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