[PATCH] PCI: rockchip-dwc: Potential error pointer dereference in probe

[Rob Herring]

On Fri, Aug 13, 2021 at 8:47 AM Robin Murphy <robin.murphy at arm.com> wrote:
>
> On 2021-08-13 14:34, Rob Herring wrote:
> > On Fri, Aug 13, 2021 at 7:55 AM Robin Murphy <robin.murphy at arm.com> wrote:
> >>
> >> On 2021-08-13 12:33, Dan Carpenter wrote:
> >>> If devm_regulator_get_optional() returns an error pointer, then we
> >>> should return it to the user.  The current code makes an exception
> >>> for -ENODEV that will result in an error pointer dereference on the
> >>> next line when it calls regulator_enable().  Remove the exception.
> >>
> >> Doesn't this break the apparent intent of the regulator being optional,
> >> though?
> >
> > I'm pretty sure 'optional' means ENODEV is never returned. So there
> > wasn't any real problem, but the check was unnecessary.
>
> In fact it's the other way round - "optional" in this case is for when
> the supply may legitimately not exist so the driver may or may not need
> to handle it, so it can return -ENODEV if a regulator isn't described by
> firmware. A non-optional regulator is assumed to represent a necessary
> supply, so if there's nothing described by firmware you get the (valid)
> dummy regulator back.

Ah yes, regulators is the oddball. Surely no one else will assume the
same behavior of _optional() variants across subsystems... ;)