linux-kernel - Re: [PATCH v2 1/2] hwmon: (lm90) Prevent integer overflow of temperature calculations

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Date:   Mon, 21 Jun 2021 15:14:40 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org
Subject: Re: [PATCH v2 1/2] hwmon: (lm90) Prevent integer overflow of
 temperature calculations

21.06.2021 15:12, Guenter Roeck пишет:
> On Mon, Jun 21, 2021 at 12:14:07AM +0300, Dmitry Osipenko wrote:
>> The minimum temperature value that is passed to the driver is unlimited
>> and value that is close to INT_MIN results in integer overflow of
>> temperature calculations made by the driver. Limit the value in order
>> to prevent the overflow. For now the overflow condition is harmless,
>> but thermal framework won't work properly once we will support the
>> set_trips() callback because it will pass INT_MIN value to the driver.
>>
> AFAICS that should only happen for lm99 because all other values
> are bound in the temp_to_xxx functions. Where else do you see an
> overflow (or underflow) ?

You're correct that the overflow affects only lm99. But why we should
ignore it?