Date:   Thu, 16 Mar 2023 20:07:18 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Zheng Wang <zyytlz.wz@163.com>
Cc:     skhan@linuxfoundation.org, p.zabel@pengutronix.de,
        biju.das.jz@bp.renesas.com, phil.edworthy@renesas.com,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        hackerzheng666@gmail.com, 1395428693sheep@gmail.com,
        alex000young@gmail.com, yoshihiro.shimoda.uh@renesas.com
Subject: Re: [PATCH v7] usb: gadget: udc: renesas_usb3: Fix use after free
 bug in  renesas_usb3_remove due to race condition
Message-ID: <ZBNo5gr1ILs5mR5z@kroah.com>
References: <20230316180850.1600867-1-zyytlz.wz@163.com>
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Precedence: bulk

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 :(