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In-Reply-To: <216eb75d-5384-4654-9e86-4a9856494ad0@alliedtelesis.co.nz>
From: Andy Shevchenko <andy.shevchenko@gmail.com>
Date: Wed, 6 Mar 2024 12:58:24 +0200
Message-ID: <CAHp75Vdi8K2mf2JSCG=e4vX+18CuNyaH-U5Q8-NGvihhyrJBJg@mail.gmail.com>
Subject: Re: [PATCH v4 1/3] auxdisplay: Add 7-segment LED display driver
To: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Cc: Andy Shevchenko <andy@kernel.org>, Geert Uytterhoeven <geert@linux-m68k.org>, 
	"robh+dt@kernel.org" <robh+dt@kernel.org>, 
	"krzysztof.kozlowski+dt@linaro.org" <krzysztof.kozlowski+dt@linaro.org>, 
	"conor+dt@kernel.org" <conor+dt@kernel.org>, "andrew@lunn.ch" <andrew@lunn.ch>, 
	"gregory.clement@bootlin.com" <gregory.clement@bootlin.com>, 
	"sebastian.hesselbarth@gmail.com" <sebastian.hesselbarth@gmail.com>, "lee@kernel.org" <lee@kernel.org>, 
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, 
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, 
	"linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, 
	"linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>
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On Wed, Mar 6, 2024 at 12:34=E2=80=AFAM Chris Packham
<Chris.Packham@alliedtelesis.co.nz> wrote:
> On 6/03/24 03:57, Andy Shevchenko wrote:
> > On Tue, Mar 05, 2024 at 09:23:07AM +0100, Geert Uytterhoeven wrote:
> >> On Tue, Mar 5, 2024 at 4:59=E2=80=AFAM Chris Packham
> >> <chris.packham@alliedtelesis.co.nz> wrote:

..

> >>> +       priv->segment_gpios =3D devm_gpiod_get_array(dev, "segment", =
GPIOD_OUT_LOW);
> >>> +       if (IS_ERR(priv->segment_gpios))
> >>> +               return PTR_ERR(priv->segment_gpios);
> >> This needs some validation of priv->segment_gpios->ndescs, else the
> >> call to gpiod_set_array_value_cansleep() in seg_led_update() may
> >> trigger an out-of-bounds access of the values bitmap.
> > Alternatively we can call gpiod_count() beforehand and check its result=
.
> Unless there are any objections I think I'll go with the ndescs check as
> it'll be easier to update to the subnode style in the future.

Either works for me.

> It does
> mean there will be some extra allocations/frees (handled via the devm_
> APIs) in the error case.


--=20
With Best Regards,
Andy Shevchenko