linux-kernel - Re: [PATCH] power: supply: Fix info use-after-free

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Message-ID: <20230919122706.anj3kfvlnxm5vboo@mercury.elektranox.org>
Date:   Tue, 19 Sep 2023 14:27:06 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Vincent Whitchurch <Vincent.Whitchurch@...s.com>
Cc:     "mazziesaccount@...il.com" <mazziesaccount@...il.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kernel <kernel@...s.com>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>
Subject: Re: [PATCH] power: supply: Fix info use-after-free

Hi,

On Tue, Sep 19, 2023 at 07:33:01AM +0000, Vincent Whitchurch wrote:
> On Mon, 2023-09-18 at 17:04 +0200, Sebastian Reichel wrote:
> > diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> > index 06e5b6b0e255..d483a81560ab 100644
> > --- a/drivers/power/supply/power_supply_sysfs.c
> > +++ b/drivers/power/supply/power_supply_sysfs.c
> > @@ -482,6 +482,13 @@ int power_supply_uevent(const struct device *dev, struct kobj_uevent_env *env)
> >         if (ret)
> >                 return ret;
> >  
> > 
> > +       /*
> > +        * Kernel generates KOBJ_REMOVE uevent in device removal path, after
> > +        * resources have been freed. Exit early to avoid use-after-free.
> > +        */
> > +       if (psy->removing)
> > +               return 0;
> > +
> >         prop_buf = (char *)get_zeroed_page(GFP_KERNEL);
> >         if (!prop_buf)
> >                 return -ENOMEM;
> > 
> > That would also cover the no-parent-device part and avoid the
> > device(s) being queried for data at device removal time, which
> > wouldn't work if the device removal happens due to a hot-unplug.
> 
> Works for me.
> 
> Tested-by: Vincent Whitchurch <vincent.whitchurch@...s.com>

Ok, I added it to power-supply's fixes branch as 3dc0bab23dba53f315c9a7b4a679e0a6d46f7c6e.

-- Sebastian

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