RE: [PATCH v2] iio: adc: ade9000: fix NULL pointer dereference in clkout registration

[Miclaus, Antoniu]

--
Antoniu Miclăuş

> -----Original Message-----
> From: Jonathan Cameron <jic23@xxxxxxxxxx>
> Sent: Monday, September 21, 2026 6:12 AM
> To: Linmao Li <lilinmao@xxxxxxxxxx>; Miclaus, Antoniu
> <Antoniu.Miclaus@xxxxxxxxxx>
> Cc: Sa, Nuno <Nuno.Sa@xxxxxxxxxx>; Hennerich, Michael
> <Michael.Hennerich@xxxxxxxxxx>; David Lechner <dlechner@xxxxxxxxxxxx>;
> Andy Shevchenko <andy@xxxxxxxxxx>; linux <linux@xxxxxxxxxx>; linux-
> iio@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v2] iio: adc: ade9000: fix NULL pointer dereference in
> clkout registration
> 
> On Mon, 31 Aug 2026 00:57:28 +0100
> Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> 
> > On Wed, 26 Aug 2026 16:31:56 +0800
> > Linmao Li <lilinmao@xxxxxxxxxx> wrote:
> >
> > > ade9000_setup_clkout() passes NULL as the register address when
> > > registering a divider clock. During clock registration, the common
> > > clock framework calls clk_divider_recalc_rate(), which dereferences
> > > the address through readl(). As a result, probing an ADE9000 configured
> > > as a clock provider with an external input clock crashes.
> > >
> > > CLKOUT passes CLKIN through without changing its rate. Register it as
> > > a 1:1 fixed-factor clock, which does not require register access.
> > >
> > > This change does not affect the configuration using the internal clock,
> > > for which the driver does not register a clock provider.
> > >
> > > Fixes: 81de7b4619fc ("iio: adc: add ade9000 support")
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > Signed-off-by: Linmao Li <lilinmao@xxxxxxxxxx>
> >
> > Looking for a tag from Antoniu for this one.
> Antoniu
> 
> Please take a look at this.

Sorry for the late response, thanks for the ping!

> 
> Jonathan
> 
> >
> > > ---
> > > Changes in v2:
> > > - Clarify that the configuration using the internal clock is unaffected.
> > >
> > >  drivers/iio/adc/ade9000.c | 5 +++--
> > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/iio/adc/ade9000.c b/drivers/iio/adc/ade9000.c
> > > index e57e24b6acdf7..4e96cc37fbedf 100644
> > > --- a/drivers/iio/adc/ade9000.c
> > > +++ b/drivers/iio/adc/ade9000.c
> > > @@ -1647,8 +1647,9 @@ static int ade9000_setup_clkout(struct device
> *dev, struct ade9000_state *st)
> > >  		return 0;
> > >
> > >  	/* CLKOUT passes through CLKIN with divider of 1 */
> > > -	clkout_hw = devm_clk_hw_register_divider(dev, "clkout",
> __clk_get_name(st->clkin),
> > > -						 CLK_SET_RATE_PARENT,
> NULL, 0, 1, 0, NULL);
> > > +	clkout_hw = devm_clk_hw_register_fixed_factor(dev, "clkout",
> > > +						      __clk_get_name(st->clkin),
> > > +						      CLK_SET_RATE_PARENT, 1,
> 1);

Reviewed-by: Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx>

> > >  	if (IS_ERR(clkout_hw))
> > >  		return dev_err_probe(dev, PTR_ERR(clkout_hw), "Failed to
> register clkout");
> > >
> > >
> > > base-commit: 6b9f23b5460818aaf199dda90210d5fc08d66c8f
> >
> >