Re: [PATCH v4 0/3] driver core: add TAINT_FORCED_BIND for when userspace manually messes with devices and drivers

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Sep 23, 2026 at 11:54:50AM +0200, Uwe Kleine-König wrote:
> > No, drivers should NOT have to do that in their .probe() function,
> > that's what we moved away from decades ago!  The match function should
> > handle all of that for you, otherwise it's contant duplication
> > everywhere that is unneeded.
> 
> Well then you have to accept that root can provoke a null pointer
> exception (e.g. by forcing the pwm-tegra driver on a device) because at
> least with today's platform bus match function such a match is ok.

Agreed, yes, root can cause a crash and can do tons of horrible things
much worse than this, that's not the issue.

That's why this taint is there, to make it obvious that this is not a
"real" bug at all.

> > Please, learn from our history, don't make the same mistakes.
> > 
> > Now I might be convinced that driver_override is the way to go here, but
> > it still feels really odd as again, bind/unbind was created as a driver
> > debugging option only, it should NOT be a normal operation that any user
> > should rely on.  The driver should "just work" properly instead, without
> > requiring manual bind work, as that's not a good model at all.
> 
> I agree in principle, but (in my case wifi) drivers are buggy sometimes
> (due to missing documentation and/or engineering effort) and being able
> to rebind the driver instead of rebooting to get a working device again
> is very useful.

Fine, use it!  Just don't expect that to be "normal".

> So yes, theoretically bind/unbind isn't needed, but theory and practise
> differ in practise.

Agreed, but again, don't rely on this as a "real" solution fo ranything.

> OK, as a compromise: Let's keep the taint (after all that's not
> destroying any functionality, just adding a hint for bug reports),
> and make driver_override opt-in, which should close an attack surface
> (mostly for fuzzers?) and so reduce the amount of bug reports instead of
> marking a part of them as tainted only.

How is that going to change anything?  Confused.

greg k-h