Re: [PATCH] iio: imu: kmx61: Fix TOCTOU race condition

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 12 May 2026 10:30:42 -0500
Maxwell Doose <m32285159@gmail.com> wrote:

> On Tue, May 12, 2026 at 10:25 AM Andy Shevchenko
> <andy.shevchenko@gmail.com> wrote:
> >
> > On Tue, May 12, 2026 at 6:17 PM Maxwell Doose <m32285159@gmail.com> wrote:  
> > >
> > > On Tue May 12, 2026 at 7:03 AM CDT, Maxwell Doose wrote:  
> > > > A Time-of-check to Time-of-use race condition is present in
> > > > kmx61_write_event_config(). Move the mutex_lock() call above it to fix
> > > > it.  
> >
> > I think you want to elaborate a bit more on this. Id est explain why
> > ev_enable_state needs to be protected. Not everybody is willing to go
> > to some site to read some AI reports and interpreted them.
> >  
> 
> Can do that for v2. I believe that it needs to be protected since
> later we set ev_enable_state to false (basically right after). Could
> be wrong of course, but Jonathan did confirm the TOCTOU.

I'd talk more about how we'd get a race.  If two calls enter the function
at the same time (which is easy to do) they may both pass this check before
getting to the lock.  Therefore we end up with at best pointless repeated
work, at worst a reference or similar count issue. You'd need to look closely
at what is protected to be sure whether it benign waste of time or a real
bug.

Jonathan

> 
> best regards,
> max
> 
> 
> 
> >  
> > > Reported-by: sashiko <sashiko-bot@kernel.org>
> > > Closes: https://sashiko.dev/#/patchset/20260507223337.48437-1-m32285159%40gmail.com  
> >
> >
> > --
> > With Best Regards,
> > Andy Shevchenko