CVE-2026-72236: s390/perf_cpum_cf: Add missing array_index_nospec() to __hw_perf_event_init()

CVE-2026-72236: s390/perf_cpum_cf: Add missing array_index_nospec() to __hw_perf_event_init()

[Greg Kroah-Hartman]

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

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

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

s390/perf_cpum_cf: Add missing array_index_nospec() to __hw_perf_event_init()

ev variable is userspace controlled via event->attr.config and used
as an array index after bounds checking, but without speculation
barriers.

Add the missing array_index_nospec() call to prevent speculative
execution.

The Linux kernel CVE team has assigned CVE-2026-72236 to this issue.


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

	Issue introduced in 3.4 with commit 212188a596d17d519842ef2173150315735b54e1 and fixed in 6.6.145 with commit 27206bb57c47bdbe33bccc78fa7f7e2a719a06b9
	Issue introduced in 3.4 with commit 212188a596d17d519842ef2173150315735b54e1 and fixed in 6.12.97 with commit a21f3615c88421df81060b6ff89220fd34094c4d
	Issue introduced in 3.4 with commit 212188a596d17d519842ef2173150315735b54e1 and fixed in 6.18.40 with commit fa1ebae4206e6afc8caa642e9eb1bbe39a9a724f
	Issue introduced in 3.4 with commit 212188a596d17d519842ef2173150315735b54e1 and fixed in 7.1.5 with commit f79dff8c721bbb1f3fc312ea55e0551c2cc28801
	Issue introduced in 3.4 with commit 212188a596d17d519842ef2173150315735b54e1 and fixed in 7.2-rc4 with commit 49145bce539117db4b6e9e83c0e5ef528e361050

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-2026-72236
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/kernel/perf_cpum_cf.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/27206bb57c47bdbe33bccc78fa7f7e2a719a06b9
	https://git.kernel.org/stable/c/a21f3615c88421df81060b6ff89220fd34094c4d
	https://git.kernel.org/stable/c/fa1ebae4206e6afc8caa642e9eb1bbe39a9a724f
	https://git.kernel.org/stable/c/f79dff8c721bbb1f3fc312ea55e0551c2cc28801
	https://git.kernel.org/stable/c/49145bce539117db4b6e9e83c0e5ef528e361050