linux-kernel - Re: [PATCH] hwmon: (adm1029) Add locking to avoid TOCTOU

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Message-ID: <1783a38c-f4ff-4564-8c76-fc5613707c5f@roeck-us.net>
Date: Wed, 26 Nov 2025 07:49:26 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Gui-Dong Han <hanguidong02@...il.com>
Cc: clabbe.montjoie@...il.com, linux-hwmon@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (adm1029) Add locking to avoid TOCTOU

On Wed, Nov 26, 2025 at 07:40:46PM +0800, Gui-Dong Han wrote:
> The function fan_show checks shared data for zero or invalid values
> before using it as a divisor. These accesses are currently lockless. If
> the data changes to zero between the check and the division, it causes a
> divide-by-zero error.
> 
> Explicitly acquire the update lock around these checks and calculations
> to ensure the data remains stable, preventing Time-of-Check to
> Time-of-Use (TOCTOU) race conditions.
> 
> Link: https://lore.kernel.org/all/CALbr=LYJ_ehtp53HXEVkSpYoub+XYSTU8Rg=o1xxMJ8=5z8B-g@mail.gmail.com/
> Signed-off-by: Gui-Dong Han <hanguidong02@...il.com>

Applied.

Thanks,
Guenter