Re: [PATCH] pinctrl: sh-pfc: fix a null pointer dereference of drive strength information

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Niklas,

On Thu, Jun 28, 2018 at 2:41 AM Niklas Söderlund
<niklas.soderlund@xxxxxxxxxxxx> wrote:
> On 2018-06-27 10:27:54 +0200, Geert Uytterhoeven wrote:
> > On Wed, Jun 27, 2018 at 8:01 AM Niklas Söderlund
> > <niklas.soderlund+renesas@xxxxxxxxxxxx> wrote:
> > > Not all SoCs describes the drive strength registers. When reading the
> > > sysfs pinconf-pins file on such a SoC this results in a null pointer
> > > dereference. Protect against this dereference and allow reading of the
> > > pinconf-pins by adding a check if the drive strength registers are
> > > described or not.
> > >
> > > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> >
> > Thanks for your patch!
> >
> > > This was found on the Eagle board and is based on the latest
> > > renesas/devel branch.
> >
> > I think the real issue is pfc-r8a77990.c setting SH_PFC_PIN_CFG_DRIVE_STRENGTH
> > without providing sh_pfc.drive_regs[].
> > Without that flag set, sh_pfc_pinconf_validate(..., PIN_CONFIG_DRIVE_STRENGTH)
> > would cause an earlier failure.
>
> Ahh I see, thanks for the pointer. I will explore this option as it
> seems like a nicer solution, thanks!

To be 100% clear: the proper solution is to add the missing drive_regs[],
not to remove the flags ;-)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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