linux-cve-announce - CVE-2023-52942: cgroup/cpuset: Fix wrong check in update_parent_subparts

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Message-ID: <2025032723-CVE-2023-52942-6a3c@gregkh>
Date: Thu, 27 Mar 2025 17:37:32 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2023-52942: cgroup/cpuset: Fix wrong check in update_parent_subparts_cpumask()

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

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

cgroup/cpuset: Fix wrong check in update_parent_subparts_cpumask()

It was found that the check to see if a partition could use up all
the cpus from the parent cpuset in update_parent_subparts_cpumask()
was incorrect. As a result, it is possible to leave parent with no
effective cpu left even if there are tasks in the parent cpuset. This
can lead to system panic as reported in [1].

Fix this probem by updating the check to fail the enabling the partition
if parent's effective_cpus is a subset of the child's cpus_allowed.

Also record the error code when an error happens in update_prstate()
and add a test case where parent partition and child have the same cpu
list and parent has task. Enabling partition in the child will fail in
this case.

[1] https://www.spinics.net/lists/cgroups/msg36254.html

The Linux kernel CVE team has assigned CVE-2023-52942 to this issue.

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

	Issue introduced in 6.1 with commit f0af1bfc27b52a4d42510051154c61bd176a8f06 and fixed in 6.1.11 with commit a2ab7f2cf5ef8f0c6212a246e681d1fe358cec1f
	Issue introduced in 6.1 with commit f0af1bfc27b52a4d42510051154c61bd176a8f06 and fixed in 6.2 with commit e5ae8803847b80fe9d744a3174abe2b7bfed222a

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-2023-52942
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:
	kernel/cgroup/cpuset.c
	tools/testing/selftests/cgroup/test_cpuset_prs.sh

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/a2ab7f2cf5ef8f0c6212a246e681d1fe358cec1f
	https://git.kernel.org/stable/c/e5ae8803847b80fe9d744a3174abe2b7bfed222a