linux-kernel - Re: [PATCH] hwmon: asus_atk0110.c fix uninitialized data access

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Message-ID: <CAKPcRGqTQK3Lp_c5fbDctPV24Q47HteVYkdo_sBVX5WoNq8YjQ@mail.gmail.com>
Date:   Thu, 23 Mar 2017 16:32:44 +0100
From:   Luca Tettamanti <kronos.it@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-hwmon@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] hwmon: asus_atk0110.c fix uninitialized data access

On 23 March 2017 at 16:03, Arnd Bergmann <arnd@...db.de> wrote:
> The latest gcc-7 snapshot adds a warning to point out that when
> atk_read_value_old or atk_read_value_new fails, we copy
> uninitialized data into sensor->cached_value:
>
> drivers/hwmon/asus_atk0110.c: In function 'atk_input_show':
> drivers/hwmon/asus_atk0110.c:651:26: error: 'value' may be used uninitialized in this function [-Werror=maybe-uninitialized]

Ops, thanks for catching this.

>
> Adding an error check avoids this. All versions of the driver
> are affected.
>
> Fixes: 2c03d07ad54d ("hwmon: Add Asus ATK0110 support")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
Reviewed-by: Luca Tettamanti <kronos.it@...il.com>


> ---
>  drivers/hwmon/asus_atk0110.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/hwmon/asus_atk0110.c b/drivers/hwmon/asus_atk0110.c
> index cccef87963e0..975c43d446f8 100644
> --- a/drivers/hwmon/asus_atk0110.c
> +++ b/drivers/hwmon/asus_atk0110.c
> @@ -646,6 +646,9 @@ static int atk_read_value(struct atk_sensor_data *sensor, u64 *value)
>                 else
>                         err = atk_read_value_new(sensor, value);
>
> +               if (err)
> +                       return err;
> +
>                 sensor->is_valid = true;
>                 sensor->last_updated = jiffies;
>                 sensor->cached_value = *value;
> --
> 2.9.0
>