linux-kernel - Re: [PATCH 6/9] thermal/core: Protect hwmon accesses to thermal operations with thermal zone mutex

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJZ5v0hMbzEdLecy_OWquOqdauBc1nsN7Q9mPkt2tOU4nEpHVw@mail.gmail.com>
Date:   Wed, 9 Nov 2022 20:19:13 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     "Rafael J . Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/9] thermal/core: Protect hwmon accesses to thermal
 operations with thermal zone mutex

On Mon, Oct 17, 2022 at 3:09 PM Guenter Roeck <linux@...ck-us.net> wrote:
>
> In preparation to protecting access to thermal operations against thermal
> zone device removal, protect hwmon accesses to thermal zone operations
> with the thermal zone mutex. After acquiring the mutex, ensure that the
> thermal zone device is registered before proceeding.
>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
>  drivers/thermal/thermal_hwmon.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/thermal_hwmon.c b/drivers/thermal/thermal_hwmon.c
> index f53f4ceb6a5d..33bfbaed4236 100644
> --- a/drivers/thermal/thermal_hwmon.c
> +++ b/drivers/thermal/thermal_hwmon.c
> @@ -77,11 +77,19 @@ temp_crit_show(struct device *dev, struct device_attribute *attr, char *buf)
>         int temperature;
>         int ret;
>
> +       mutex_lock(&tz->lock);
> +
> +       if (!device_is_registered(&tz->device)) {
> +               ret = -ENODEV;
> +               goto unlock;
> +       }
> +
>         ret = tz->ops->get_crit_temp(tz, &temperature);

Again, I would do it this way:

        if (device_is_registered(&tz->device))
                ret = tz->ops->get_crit_temp(tz, &temperature);
        else
                ret = -ENODEV;

And I wouldn't change the code below (the ternary operator is out of
fashion in particular).

> -       if (ret)
> -               return ret;
>
> -       return sprintf(buf, "%d\n", temperature);
> +unlock:
> +       mutex_unlock(&tz->lock);
> +
> +       return ret ? ret : sprintf(buf, "%d\n", temperature);
>  }
>
>
> --