Re: [PATCH] firmware: arm_scmi: Fix OOB in scmi_power_name_get()

[Cristian Marussi <cristian.marussi@arm.com>]

On Fri, May 15, 2026 at 01:29:27PM +0200, Geert Uytterhoeven wrote:
> Hi Dan,
> 

Hi all,

> On Fri, 15 May 2026 at 12:28, Dan Carpenter <error27@gmail.com> wrote:
> > On Fri, May 15, 2026 at 11:59:15AM +0200, Geert Uytterhoeven wrote:
> > > scmi_power_name_get() does not validate the domain number passed by the
> > > external caller, which may lead to an out-of-bounds access.
> >
> > Is an external caller an out of tree caller?  So far as I can see this
> 
> I meant a caller outside drivers/firmware/arm_scmi/.
> 
> > is only called by scmi_pm_domain_probe().
> >
> >         scmi_pd->name = power_ops->name_get(ph, i);
> >
> > where i < num_domains.
> 
> You are right. But this seems to be only API implementation in
> drivers/firmware/arm_scmi/ that does not validate the passed domain
> number.
>

Yes we tend to validate protocol operations calls even if apparently
safe from teh caller perspective...indeed I have this fixed locally
since ages in an horrible patch, that does a lot more, and that I
never posted :P

Usually, if it is worth, we also build an internal domain get helper to
reuse across the protocol unit...but here really there are only 2 call-sites.

What I am not sure is what to return: "unknown" is safer as of now than NULL
for sure, but really, what happened is NOT that the name was "unknown" (which
by itself would be out-of-spec behaviour) it is more that the whole domain that
was referred to that was invalid and NOT existent...

....mmm I suppose we are opening another can of worms here :P

Thanks,
Cristian