linux-kernel - Re: [PATCH v2] power: supply: ds2782: fix possible use-after-free on remove

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Date:   Tue, 12 Feb 2019 23:30:25 +0100
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Sven Van Asbroeck <thesven73@...il.com>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] power: supply: ds2782: fix possible use-after-free on
 remove

Hi,

On Tue, Feb 12, 2019 at 11:21:49AM -0500, Sven Van Asbroeck wrote:
> In remove(), use cancel_delayed_work_sync() to cancel the
> delayed work. Otherwise there's a chance that this work
> will continue to run until after the device has been removed.
> 
> While we're here, fix the deallocation order in remove(),
> to correspond to the inverse of the probe() allocation
> order. This guarantees that any remaining work can run
> to completion with all driver structures still intact.
> 
> This issue was detected with the help of Coccinelle.
> 
> Signed-off-by: Sven Van Asbroeck <TheSven73@...il.com>
> ---

Thanks, queued to power-supply's linux-next branch.

-- Sebastian

> v2: fix silly use-after-free in remove()
> 
>  drivers/power/supply/ds2782_battery.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/power/supply/ds2782_battery.c b/drivers/power/supply/ds2782_battery.c
> index 019c58493e3d..04b0fe7d7d62 100644
> --- a/drivers/power/supply/ds2782_battery.c
> +++ b/drivers/power/supply/ds2782_battery.c
> @@ -319,17 +319,17 @@ static void ds278x_power_supply_init(struct power_supply_desc *battery)
>  static int ds278x_battery_remove(struct i2c_client *client)
>  {
>  	struct ds278x_info *info = i2c_get_clientdata(client);
> +	int id = info->id;
>  
>  	power_supply_unregister(info->battery);
> +	cancel_delayed_work_sync(&info->bat_work);
>  	kfree(info->battery_desc.name);
> +	kfree(info);
>  
>  	mutex_lock(&battery_lock);
> -	idr_remove(&battery_id, info->id);
> +	idr_remove(&battery_id, id);
>  	mutex_unlock(&battery_lock);
>  
> -	cancel_delayed_work(&info->bat_work);
> -
> -	kfree(info);
>  	return 0;
>  }
>  
> -- 
> 2.17.1
> 

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