usb: gadget: udc: renesas_usb3: Fix use after free bug in renesas_usb…

…3_remove due to race condition

In renesas_usb3_probe, role_work is bound with renesas_usb3_role_work.
renesas_usb3_start will be called to start the work.

If we remove the driver which will call usbhs_remove, there may be
an unfinished work. The possible sequence is as follows:

CPU0                  			CPU1

                    			 renesas_usb3_role_work
renesas_usb3_remove
usb_role_switch_unregister
device_unregister
kfree(sw)
//free usb3->role_sw
                    			 usb_role_switch_set_role
                    			 //use usb3->role_sw

The usb3->role_sw could be freed under such circumstance and then
used in usb_role_switch_set_role.

This bug was found by static analysis. And note that removing a
driver is a root-only operation, and should never happen in normal
case. But the root user may directly remove the device which
will also trigger the remove function.

Fix it by canceling the work before cleanup in the renesas_usb3_remove.

Fixes: 39facfa ("usb: gadget: udc: renesas_usb3: Add register of usb role switch")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20230320062931.505170-1-zyytlz.wz@163.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/renesas_usb3.c

@@ -2660,6 +2660,7 @@ static int renesas_usb3_remove(struct platform_device *pdev)
 	debugfs_remove_recursive(usb3->dentry);
 	device_remove_file(&pdev->dev, &dev_attr_role);
 
+	cancel_work_sync(&usb3->role_work);
 	usb_role_switch_unregister(usb3->role_sw);
 
 	usb_del_gadget_udc(&usb3->gadget);