linux-cve-announce - CVE-2023-53205: KVM: s390/diag: fix racy access of physical cpu number in diag 9c handler

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Message-ID: <2025091510-CVE-2023-53205-9a2b@gregkh>
Date: Mon, 15 Sep 2025 16:21:39 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53205: KVM: s390/diag: fix racy access of physical cpu number in diag 9c handler

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

KVM: s390/diag: fix racy access of physical cpu number in diag 9c handler

We do check for target CPU == -1, but this might change at the time we
are going to use it. Hold the physical target CPU in a local variable to
avoid out-of-bound accesses to the cpu arrays.

The Linux kernel CVE team has assigned CVE-2023-53205 to this issue.


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

	Issue introduced in 5.13 with commit 87e28a15c42cc592009c32a8c20e5789059027c2 and fixed in 5.15.121 with commit a9ccf140a2a03a0ae82be4bdfbdd17bdaea72ff5
	Issue introduced in 5.13 with commit 87e28a15c42cc592009c32a8c20e5789059027c2 and fixed in 6.1.39 with commit 86bfb18bad60fc468e5f112cbbd918462a8dd435
	Issue introduced in 5.13 with commit 87e28a15c42cc592009c32a8c20e5789059027c2 and fixed in 6.4.4 with commit dc7e0192c470a53d847c79a2796f9ac429477a26
	Issue introduced in 5.13 with commit 87e28a15c42cc592009c32a8c20e5789059027c2 and fixed in 6.5 with commit 0bc380beb78aa352eadbc21d934dd9606fcee808

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-2023-53205
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:
	arch/s390/kvm/diag.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/a9ccf140a2a03a0ae82be4bdfbdd17bdaea72ff5
	https://git.kernel.org/stable/c/86bfb18bad60fc468e5f112cbbd918462a8dd435
	https://git.kernel.org/stable/c/dc7e0192c470a53d847c79a2796f9ac429477a26
	https://git.kernel.org/stable/c/0bc380beb78aa352eadbc21d934dd9606fcee808