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From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Thu, 16 Mar 2023 21:28:19 +0800
Message-ID: <CAJedcCxxuRjzaAyUk2qKkT6e-mFsgEhL_fmg+MJ9546rV4TYrQ@mail.gmail.com>
Subject: Re: [PATCH v3] usb: gadget: udc: renesas_usb3: Fix use after free bug
 in renesas_usb3_remove due to race condition
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Zheng Wang <zyytlz.wz@163.com>, p.zabel@pengutronix.de,
        biju.das.jz@bp.renesas.com, phil.edworthy@renesas.com,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        1395428693sheep@gmail.com, alex000young@gmail.com,
        yoshihiro.shimoda.uh@renesas.com
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Greg KH <gregkh@linuxfoundation.org> =E4=BA=8E2023=E5=B9=B43=E6=9C=8816=E6=
=97=A5=E5=91=A8=E5=9B=9B 18:55=E5=86=99=E9=81=93=EF=BC=9A
>
> On Tue, Mar 14, 2023 at 12:51:28AM +0800, Zheng Wang wrote:
> > In renesas_usb3_probe, &usb3->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
> >
> > 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
> >
> > Fixes: 39facfa01c9f ("usb: gadget: udc: renesas_usb3: Add register of u=
sb role switch")
> > Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> > Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> > ---
> > v3:
> > - modify the commit message to make it clearer suggested by Yoshihiro S=
himoda
>
> I see 2 v3 patches in the mailing list, which is obviously not correct.
>
> Please resubmit a v4 properly.
>

Hi Greg,

Thanks for your kind reminder. I'll resubmit a v4 patch later.

Best regards,
Zheng

> thanks,
>
> greg k-h