linux-cve-announce - CVE-2025-68179: s390: Disable ARCH_WANT_OPTIMIZE_HUGETLB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2025121631-CVE-2025-68179-6ce9@gregkh>
Date: Tue, 16 Dec 2025 14:43:40 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68179: s390: Disable ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP

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

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

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

s390: Disable ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP

As reported by Luiz Capitulino enabling HVO on s390 leads to reproducible
crashes. The problem is that kernel page tables are modified without
flushing corresponding TLB entries.

Even if it looks like the empty flush_tlb_all() implementation on s390 is
the problem, it is actually a different problem: on s390 it is not allowed
to replace an active/valid page table entry with another valid page table
entry without the detour over an invalid entry. A direct replacement may
lead to random crashes and/or data corruption.

In order to invalidate an entry special instructions have to be used
(e.g. ipte or idte). Alternatively there are also special instructions
available which allow to replace a valid entry with a different valid
entry (e.g. crdte or cspg).

Given that the HVO code currently does not provide the hooks to allow for
an implementation which is compliant with the s390 architecture
requirements, disable ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP again, which is
basically a revert of the original patch which enabled it.

The Linux kernel CVE team has assigned CVE-2025-68179 to this issue.

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

	Issue introduced in 6.2 with commit 00a34d5a99c0631bd780b14cbe3813d0b39c3886 and fixed in 6.6.117 with commit 7088465f10816d9425b95740b37c95f082041d76
	Issue introduced in 6.2 with commit 00a34d5a99c0631bd780b14cbe3813d0b39c3886 and fixed in 6.12.58 with commit 5e23918e4352288323d13fb511116cdea0234b71
	Issue introduced in 6.2 with commit 00a34d5a99c0631bd780b14cbe3813d0b39c3886 and fixed in 6.17.8 with commit d4a8238e5729505b7394ccb007e5dc3e557aa66b
	Issue introduced in 6.2 with commit 00a34d5a99c0631bd780b14cbe3813d0b39c3886 and fixed in 6.18 with commit 64e2f60f355e556337fcffe80b9bcff1b22c9c42

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-2025-68179
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/Kconfig

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/7088465f10816d9425b95740b37c95f082041d76
	https://git.kernel.org/stable/c/5e23918e4352288323d13fb511116cdea0234b71
	https://git.kernel.org/stable/c/d4a8238e5729505b7394ccb007e5dc3e557aa66b
	https://git.kernel.org/stable/c/64e2f60f355e556337fcffe80b9bcff1b22c9c42