CVE-2026-74547: hwmon: (adt7470) Fix busy-loop and I2C flooding in update thread

From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

hwmon: (adt7470) Fix busy-loop and I2C flooding in update thread

When userspace configures 'auto_update_interval' to 0 via sysfs, the
background kthread executes schedule_timeout_interruptible(0), which
returns immediately.

If 'num_temp_sensors' is concurrently or previously set to 0, the
msleep_interruptible() delay inside adt7470_read_temperatures() also
becomes 0. This combination forces the background thread into a tight,
unbounded busy-loop, hogging the CPU and flooding the I2C bus with a
continuous stream of transactions.

Fix this vulnerability by raising the lower limit of the clamp_val in
auto_update_interval_store() from 0 to 500 milliseconds. This guarantees
a reasonable minimum sleep window between sensor updates, protecting the
system from intentional or accidental I2C bus denial of service.

The Linux kernel CVE team has assigned CVE-2026-74547 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 2.6.29 with commit 89fac11cb3e7c5860c425dba14845c09ccede39d and fixed in 6.6.151 with commit 1a42bd72a66205e439db1d1142442b62d393408a
	Issue introduced in 2.6.29 with commit 89fac11cb3e7c5860c425dba14845c09ccede39d and fixed in 6.12.103 with commit 38e6b5ce5794ff09442231cc171c2be5e900bab3
	Issue introduced in 2.6.29 with commit 89fac11cb3e7c5860c425dba14845c09ccede39d and fixed in 6.18.44 with commit 82d65f7ef11edcea0228745440b8b4b1f222c34c
	Issue introduced in 2.6.29 with commit 89fac11cb3e7c5860c425dba14845c09ccede39d and fixed in 7.1.8 with commit 5ea299c3aa42a827f6a863eeead6de3525bbb17a
	Issue introduced in 2.6.29 with commit 89fac11cb3e7c5860c425dba14845c09ccede39d and fixed in 7.2-rc6 with commit cb0b7f9c43b0abbd422a7e4c2c85e91db429207c

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-74547
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/hwmon/adt7470.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/1a42bd72a66205e439db1d1142442b62d393408a
	https://git.kernel.org/stable/c/38e6b5ce5794ff09442231cc171c2be5e900bab3
	https://git.kernel.org/stable/c/82d65f7ef11edcea0228745440b8b4b1f222c34c
	https://git.kernel.org/stable/c/5ea299c3aa42a827f6a863eeead6de3525bbb17a
	https://git.kernel.org/stable/c/cb0b7f9c43b0abbd422a7e4c2c85e91db429207c