Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Wed, 29 Mar 2023 16:38:55 +0200 | Subject | Re: [PATCH -next] thermal/drivers/thermal_hwmon: Fix a kernel NULL pointer dereference |
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On Wed, Mar 29, 2023 at 4:16 PM Daniel Lezcano <daniel.lezcano@linaro.org> wrote: > > On 29/03/2023 14:06, Rafael J. Wysocki wrote: > > On Wed, Mar 29, 2023 at 11:57 AM Daniel Lezcano > > <daniel.lezcano@linaro.org> wrote: > >> > >> On 29/03/2023 11:00, Zhang Rui wrote: > >>> When the hwmon device node of a thermal zone device is not found, > >>> using hwmon->device causes a kernel NULL pointer dereference. > >>> > >>> Reported-by: Preble Adam C <adam.c.preble@intel.com> > >>> Signed-off-by: Zhang Rui <rui.zhang@intel.com> > >>> --- > >>> Fixes: dec07d399cc8 ("thermal: Don't use 'device' internal thermal zone structure field") > >>> dec07d399cc8 is a commit in the linux-next branch of linux-pm repo. > >>> I'm not sure if the Fix tag applies to such commit or not. > >> > >> Actually it reverts the work done to encapsulate the thermal zone device > >> structure. > > > > So maybe instead of the wholesale switch to using "driver-specific" > > device pointers for printing messages, something like > > thermal_zone_debug/info/warn/error() taking a thermal zone pointer as > > the first argument can be defined? > > > > At least this particular bug could be avoided this way. > > Actually we previously said the thermal_hwmon can be considered as part > of the thermal core code, so we can keep using tz->device. > > I'll drop this change from the series.
But it's there in my thermal branch already.
Do you want to revert the thermal_hwmon.c part of commit dec07d399cc8?
> On the other side, adding more thermal_zone_debug/info.. gives > opportunities to external components of the core thermal framework to > write thermal zone device related message. I'm not sure that is a good > thing, each writer should stay in its namespace, no ?
IMV whoever is allowed to use a thermal zone pointer should also be allowed to print messages related to its use, especially debug ones.
"Encapsulation" means that the members of a thermal zone device object should not be accessed directly by its users other than the core, not that it cannot be used as a message tag.
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