Subject: CVE-2024-36932: thermal/debugfs: Prevent use-after-free from occurring after cdev removal

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

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

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

thermal/debugfs: Prevent use-after-free from occurring after cdev removal

Since thermal_debug_cdev_remove() does not run under cdev->lock, it can
run in parallel with thermal_debug_cdev_state_update() and it may free
the struct thermal_debugfs object used by the latter after it has been
checked against NULL.

If that happens, thermal_debug_cdev_state_update() will access memory
that has been freed already causing the kernel to crash.

Address this by using cdev->lock in thermal_debug_cdev_remove() around
the cdev->debugfs value check (in case the same cdev is removed at the
same time in two different threads) and its reset to NULL.

Cc :6.8+ <[email-masked]> # 6.8+

The Linux kernel CVE team has assigned CVE-2024-36932 to this issue.

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

	Issue introduced in 6.8 with commit 755113d76786 and fixed in 6.8.10 with commit c1279dee3336
	Issue introduced in 6.8 with commit 755113d76786 and fixed in 6.9 with commit d351eb0ab04c

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-2024-36932
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/thermal/thermal_debugfs.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/c1279dee33369e2525f532364bb87207d23b9481
	https://git.kernel.org/stable/c/d351eb0ab04c3e8109895fc33250cebbce9c11da