From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Alexandru Ardelean <alexandru.ardelean@analog.com>,
Mark Brown <broonie@kernel.org>, David Jander <david@protonic.nl>,
kernel@pengutronix.de, linux-kernel@vger.kernel.org,
linux-input@vger.kernel.org, linux-spi@vger.kernel.org
Subject: Re: [PATCH v1] Input: touchscreen: ads7846.c: fix integer overflow on Rt calculation
Date: Tue, 17 Nov 2020 16:31:48 -0800 [thread overview]
Message-ID: <20201118003148.GE2009714@dtor-ws> (raw)
In-Reply-To: <20201113112240.1360-1-o.rempel@pengutronix.de>
On Fri, Nov 13, 2020 at 12:22:40PM +0100, Oleksij Rempel wrote:
> In some rare cases the 32 bit Rt value will overflow if z2 and x is max,
> z1 is minimal value and x_plate_ohms is relatively high (for example 800
> ohm). This would happen on some screen age with low pressure.
>
> There are two possible fixes:
> - make Rt 64bit
> - reorder calculation to avoid overflow
>
> The second variant seems to be preferable, since 64 bit calculation on
> 32 bit system is a bit more expensive.
>
> Fixes: ffa458c1bd9b6f653008d450f337602f3d52a646 ("spi: ads7846 driver")
> Co-Developed-by: David Jander <david@protonic.nl>
> Signed-off-by: David Jander <david@protonic.nl>
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Applied, thank you.
--
Dmitry
prev parent reply other threads:[~2020-11-18 0:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 11:22 [PATCH v1] Input: touchscreen: ads7846.c: fix integer overflow on Rt calculation Oleksij Rempel
2020-11-18 0:31 ` Dmitry Torokhov [this message]
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