linux-kernel - Re: [PATCH 0/9] thermal/core: Protect thermal device operations against removal

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Date:   Wed, 9 Nov 2022 20:30:00 +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 0/9] thermal/core: Protect thermal device operations
 against removal

Hi Guenter,

Sorry for the delay.

On Wed, Nov 2, 2022 at 7:50 PM Guenter Roeck <linux@...ck-us.net> wrote:
>
> Hi,
>
> On Mon, Oct 17, 2022 at 06:09:01AM -0700, Guenter Roeck wrote:
> > Accesses to thermal zones, and with it to thermal zone device operations,
> > are still possible after the thermal zone device has been unregistered.
> > For example, thermal_zone_get_temp() can be called from temp_show()
> > in thermal_sysfs.c if the sysfs attribute was opened before the thermal
> > device was unregistered. This is problematic and may result in crashes
> > since the operations data structure and the underlying code may be gone
> > when the calls are made.
> >
> > The following series solves the problem by protecting accesses to thermal
> > device operations with the thermal device mutex, and by verifying that the
> > thermal device is still registered after the mutex has been acquired.
> >
> > This was previously sent as RFC/RFT as single patch [1]. The code was reworked
> > to match thermal subsystem changes made between v6.0 and v6.1, and it was
> > split into several patches to simplify review.
> >
>
> Any thoughts / comments / feedback on this series ?

I have reviewed the series now and haven't found any major issues in it.

I've posted some minor comments in separate replies to individual
patches.  If they are addressed, I can queue up the series for 6.2.

Cheers!


> > [1] https://lore.kernel.org/linux-pm/20221004033936.1047691-1-linux@roeck-us.net/
> >
> > ----------------------------------------------------------------
> > Guenter Roeck (9):
> >       thermal/core: Destroy thermal zone device mutex in release function
> >       thermal/core: Delete device under thermal device zone lock
> >       thermal/core: Ensure that thermal device is registered in thermal_zone_get_temp
> >       thermal/core: Move parameter validation from __thermal_zone_get_temp to thermal_zone_get_temp
> >       thermal/core: Introduce locked version of thermal_zone_device_update
> >       thermal/core: Protect hwmon accesses to thermal operations with thermal zone mutex
> >       thermal/core: Protect sysfs accesses to thermal operations with thermal zone mutex
> >       thermal/core: Remove thermal_zone_set_trips()
> >       thermal/core: Protect thermal device operations against thermal device removal
> >
> >  drivers/thermal/thermal_core.c    | 76 ++++++++++++++++++++++++--------------
> >  drivers/thermal/thermal_core.h    |  3 +-
> >  drivers/thermal/thermal_helpers.c | 65 ++++++++++++++++++++++-----------
> >  drivers/thermal/thermal_hwmon.c   | 14 +++++--
> >  drivers/thermal/thermal_sysfs.c   | 77 +++++++++++++++++++++++++++++++++------
> >  5 files changed, 169 insertions(+), 66 deletions(-)