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

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Date:   Tue, 19 Sep 2023 07:33:01 +0000
From:   Vincent Whitchurch <Vincent.Whitchurch@...s.com>
To:     "sre@...nel.org" <sre@...nel.org>,
        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

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>