linux-kernel - Re: [PATCH] hwmon: (max16065) Use local variable to avoid TOCTOU

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Message-ID: <2fc6a617-3537-4c13-a8cb-1fbb79817319@roeck-us.net>
Date: Fri, 28 Nov 2025 08:36:38 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Gui-Dong Han <hanguidong02@...il.com>
Cc: linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] hwmon: (max16065) Use local variable to avoid TOCTOU

On Fri, Nov 28, 2025 at 08:47:09PM +0800, Gui-Dong Han wrote:
> In max16065_current_show, data->curr_sense is read twice: once for the
> error check and again for the calculation. Since
> i2c_smbus_read_byte_data returns negative error codes on failure, if the
> data changes to an error code between the check and the use, ADC_TO_CURR
> results in an incorrect calculation.
> 
> Read data->curr_sense into a local variable to ensure consistency. Note
> that data->curr_gain is constant and safe to access directly.
> 
> This aligns max16065_current_show with max16065_input_show, which
> already uses a local variable for the same reason.
> 
> Link: https://lore.kernel.org/all/CALbr=LYJ_ehtp53HXEVkSpYoub+XYSTU8Rg=o1xxMJ8=5z8B-g@mail.gmail.com/
> Fixes: f5bae2642e3d ("hwmon: Driver for MAX16065 System Manager and compatibles")
> Cc: stable@...r.kernel.org
> Signed-off-by: Gui-Dong Han <hanguidong02@...il.com>

Applied.

Thanks,
Guenter