CVE-2026-64038: hwmon: (lm90) Stop work before releasing hwmon device

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

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

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

hwmon: (lm90) Stop work before releasing hwmon device

Sashiko reports:

In lm90_probe(), the devm action to cancel the alert_work and report_work
(lm90_restore_conf) is registered in lm90_init_client() before
devm_hwmon_device_register_with_info() is called.

Because devm executes cleanup actions in reverse order during module
unbind or probe failure, the hwmon device is unregistered and freed first.

If lm90_alert_work() or lm90_report_alarms() runs in the window between
the hwmon device being freed and the delayed works being cancelled,
lm90_update_alarms() will dereference the freed data->hwmon_dev here.

Fix the problem by canceling the workers separately after registering
the hwmon device and before registering the interrupt handler. This ensures
that the workers are canceled after interrupts are disabled and before
the hwmon device is released. Add "shutdown" flag to indicate that device
shutdown is in progress to prevent workers from being re-armed.

The Linux kernel CVE team has assigned CVE-2026-64038 to this issue.


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

	Issue introduced in 6.0 with commit f6d0775119fb905fb02eafa98d575cf8ee792d46 and fixed in 6.18.34 with commit c98107817b0f6cdf51adc5e84e75c39ee25d8b28
	Issue introduced in 6.0 with commit f6d0775119fb905fb02eafa98d575cf8ee792d46 and fixed in 7.0.11 with commit 479e297526aeb19c745eac5c1897f455f83dc5f8
	Issue introduced in 6.0 with commit f6d0775119fb905fb02eafa98d575cf8ee792d46 and fixed in 7.1 with commit b09a45601094c7f4ec4db8090b825fa61e169d93

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-2026-64038
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/lm90.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/c98107817b0f6cdf51adc5e84e75c39ee25d8b28
	https://git.kernel.org/stable/c/479e297526aeb19c745eac5c1897f455f83dc5f8
	https://git.kernel.org/stable/c/b09a45601094c7f4ec4db8090b825fa61e169d93