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In-Reply-To: <e5b1ee16-796e-43fe-b703-3ce06aed364d@mercury.local>
From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Sat, 11 Mar 2023 00:24:18 +0800
Message-ID: <CAJedcCwt7agR8Y76Rsj5d9HK2oYJZi_QGh11v97L31QR+RDZ+A@mail.gmail.com>
Subject: Re: [PATCH] power: supply: da9150: Fix use after free bug in
 da9150_charger_remove due to race condition
To:     Sebastian Reichel <sebastian.reichel@collabora.com>
Cc:     Zheng Wang <zyytlz.wz@163.com>, support.opensource@diasemi.com,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
        1395428693sheep@gmail.com, alex000young@gmail.com
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Sebastian Reichel <sebastian.reichel@collabora.com> =E4=BA=8E2023=E5=B9=B43=
=E6=9C=8810=E6=97=A5=E5=91=A8=E4=BA=94 07:39=E5=86=99=E9=81=93=EF=BC=9A
>
> Hi,
>
> On Fri, Mar 10, 2023 at 02:10:36AM +0800, Zheng Wang wrote:
> > In da9150_charger_probe, &charger->otg_work is bound with
> > da9150_charger_otg_work. da9150_charger_otg_ncb may be
> > called to start the work.
> >
> > If we remove the module which will call da9150_charger_remove
> >  to make cleanup, there may be a unfinished work. The possible
> >   sequence is as follows:
> >
> > Fix it by canceling the work before cleanup in the mtk_jpeg_remove
>
> mtk_jpeg_remove?

Sorry that's mistake. I will correct it in the next version of patch.

>
> >
> > CPU0                  CPUc1
> >
> >                     |da9150_charger_otg_work
> > da9150_charger_remove      |
> > power_supply_unregister  |
> > device_unregister   |
> > power_supply_dev_release|
> > kfree(psy)          |
> >                     |
> >                     |         power_supply_changed(charger->usb);
> >                     |   //use
> > Fixes: c1a281e34dae ("power: Add support for DA9150 Charger")
> > Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> > ---
>
> Looks correct to me, but the cancel_work_sync should happen after
> usb_unregister_notifier(), otherwise there is still a race
> condition.

Yes, I agree that. Thanks for pointing that out. Will do in the next path.

Best regards,
Zheng

>
> >  drivers/power/supply/da9150-charger.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/power/supply/da9150-charger.c b/drivers/power/supp=
ly/da9150-charger.c
> > index 14da5c595dd9..41b68f2f6ed8 100644
> > --- a/drivers/power/supply/da9150-charger.c
> > +++ b/drivers/power/supply/da9150-charger.c
> > @@ -642,6 +642,7 @@ static int da9150_charger_remove(struct platform_de=
vice *pdev)
> >       struct da9150_charger *charger =3D platform_get_drvdata(pdev);
> >       int irq;
> >
> > +     cancel_work_sync(&charger->otg_work);
> >       /* Make sure IRQs are released before unregistering power supplie=
s */
> >       irq =3D platform_get_irq_byname(pdev, "CHG_VBUS");
> >       free_irq(irq, charger);
> > --
> > 2.25.1
> >