Nikita Zhandarovich 5a15f8d87a hwmon: (it87) Clamp negative values to zero in set_fan()
[ Upstream commit 7f8581c70a ]

set_fan() parses user input with kstrtol() and passes the resulting
value to FAN16_TO_REG() on chips with 16-bit fan support.

Negative fan speeds are not meaningful and should be rejected before
conversion. Worst scenario, one may be able to abuse undefined
behaviour of signed overflow to possibly induce rpm * 2 == 0 in
FAN16_TO_REG(), thus causing a division by zero.

Instead, clamp val < 0 to zero and keep the conversion in its valid
input domain, avoiding unsafe arithmetic in the register conversion
path.

Found by Linux Verification Center (linuxtesting.org) with static
analysis tool SVACE.

Fixes: 17d648bf57 ("it87: Add support for the IT8716F")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Link: https://lore.kernel.org/r/20260529141839.1639287-1-n.zhandarovich@fintech.ru
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2026-07-24 16:03:09 +02:00
2026-07-24 16:03:06 +02:00
2026-05-23 13:03:09 +02:00
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2026-05-23 13:03:09 +02:00
2026-07-04 13:42:28 +02:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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