On Wed, Sep 21, 2022 at 8:16 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> On 9/21/22 16:31, Li Zhong wrote:
> > Hello,
> >
> > My static analysis tool reports a possible bug in the adm9240 driver in Linux
> > v6.0:
> >
> > drivers/hwmon/adm9240.c:
> >
> > adm9240_read()
> > adm9240_fan_read() --> Line 509
> > adm9240_write_fan_div()
> >
> > adm9240_write_fan_div() says 'callers must hold
> > data->update_lock'. However, it seems like the context does
> > not hold the lock it requires. So it may cause data race when
> > setting new fan div.
> >
> > I am not quite sure whether this is a real bug. Any feedback would be
> > appreciated!
> >
>
> You are correct, the code in adm9240_fan_read() should acquire
> the mutex before calling adm9240_write_fan_div() and while
> manipulating data->fan_div[channel].
>
> Guenter
Thanks for your patient reply! Can I submit a patch on this? The draft will
be something like:
+ mutex_lock(&data->update_lock)
err = adm9240_write_fan_div(data, channel, ++data->fan_div[channel]);
if (err)
return err;
+ mutex_unlock(&data->update_lock);
Let me know if you have any suggestions!
