Re: [PATCH v7] usb: gadget: udc: renesas_usb3: Fix use after free bug in renesas_usb3_remove due to race condition

[Greg KH]

On Fri, Mar 17, 2023 at 02:08:50AM +0800, Zheng Wang wrote:
> 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:
> 
> Fix it by canceling the work before cleanup in the renesas_usb3_remove.
> 
> Note that removing a driver is a root-only operation, and should never
> happen.
> 
> 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

This still isn't working :(