linux-cve-announce - CVE-2023-53254: cacheinfo: Fix shared_cpu_map to handle shared caches at different levels

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Message-ID: <2025091503-CVE-2023-53254-0aa0@gregkh>
Date: Mon, 15 Sep 2025 16:46:29 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53254: cacheinfo: Fix shared_cpu_map to handle shared caches at different levels

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

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

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

cacheinfo: Fix shared_cpu_map to handle shared caches at different levels

The cacheinfo sets up the shared_cpu_map by checking whether the caches
with the same index are shared between CPUs. However, this will trigger
slab-out-of-bounds access if the CPUs do not have the same cache hierarchy.
Another problem is the mismatched shared_cpu_map when the shared cache does
not have the same index between CPUs.

CPU0	I	D	L3
index	0	1	2	x
	^	^	^	^
index	0	1	2	3
CPU1	I	D	L2	L3

This patch checks each cache is shared with all caches on other CPUs.

The Linux kernel CVE team has assigned CVE-2023-53254 to this issue.


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

	Fixed in 6.1.18 with commit 2f588d0345d69a35e451077afed428fd057a5e34
	Fixed in 6.2.5 with commit dea49f2993f57d8a2df2cacb0bf649ef49b28879
	Fixed in 6.3 with commit 198102c9103fc78d8478495971947af77edb05c1

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-2023-53254
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/base/cacheinfo.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/2f588d0345d69a35e451077afed428fd057a5e34
	https://git.kernel.org/stable/c/dea49f2993f57d8a2df2cacb0bf649ef49b28879
	https://git.kernel.org/stable/c/198102c9103fc78d8478495971947af77edb05c1