usb: gadget: tegra-xudc: Fix possible use-after-free in tegra_xudc_remove()

This driver's remove path calls cancel_delayed_work(). However, that
function does not wait until the work function finishes. This means
that the callback function may still be running after the driver's
remove function has finished, which would result in a use-after-free.

Fix by calling cancel_delayed_work_sync(), which ensures that
the work is properly cancelled, no longer running, and unable
to re-schedule itself.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20210407092947.3271507-1-yangyingliang@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/tegra-xudc.c

@@ -3883,7 +3883,7 @@ static int tegra_xudc_remove(struct platform_device *pdev)
 
 	pm_runtime_get_sync(xudc->dev);
 
-	cancel_delayed_work(&xudc->plc_reset_work);
+	cancel_delayed_work_sync(&xudc->plc_reset_work);
 	cancel_work_sync(&xudc->usb_role_sw_work);
 
 	usb_del_gadget_udc(&xudc->gadget);