linux-cve-announce - CVE-2022-49640: sysctl: Fix data races in proc_douintvec

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Message-ID: <2025022618-CVE-2022-49640-96ed@gregkh>
Date: Wed, 26 Feb 2025 03:23:23 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49640: sysctl: Fix data races in proc_douintvec_minmax().

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

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

sysctl: Fix data races in proc_douintvec_minmax().

A sysctl variable is accessed concurrently, and there is always a chance
of data-race.  So, all readers and writers need some basic protection to
avoid load/store-tearing.

This patch changes proc_douintvec_minmax() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side.  For now,
proc_douintvec_minmax() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.

The Linux kernel CVE team has assigned CVE-2022-49640 to this issue.

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

	Issue introduced in 4.13 with commit 61d9b56a89208d8cccd0b4cfec7e6959717e16e3 and fixed in 5.10.132 with commit e3a2144b3b6bf9ecafd91087c8b8b48171ec19df
	Issue introduced in 4.13 with commit 61d9b56a89208d8cccd0b4cfec7e6959717e16e3 and fixed in 5.15.56 with commit 40e0477a7371d101c55b69d9c32a7a1ed82ab5ea
	Issue introduced in 4.13 with commit 61d9b56a89208d8cccd0b4cfec7e6959717e16e3 and fixed in 5.18.13 with commit b60eddf98b9716651069dfda296c91311a7a6293
	Issue introduced in 4.13 with commit 61d9b56a89208d8cccd0b4cfec7e6959717e16e3 and fixed in 5.19 with commit 2d3b559df3ed39258737789aae2ae7973d205bc1

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-2022-49640
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/sysctl.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/e3a2144b3b6bf9ecafd91087c8b8b48171ec19df
	https://git.kernel.org/stable/c/40e0477a7371d101c55b69d9c32a7a1ed82ab5ea
	https://git.kernel.org/stable/c/b60eddf98b9716651069dfda296c91311a7a6293
	https://git.kernel.org/stable/c/2d3b559df3ed39258737789aae2ae7973d205bc1