CVE-2026-64558: s390/pkey: Check length in pkey_pckmo handler implementation

CVE-2026-64558: s390/pkey: Check length in pkey_pckmo handler implementation

[Greg Kroah-Hartman]

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

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

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

s390/pkey: Check length in pkey_pckmo handler implementation

Explicitly check the length of the target buffer in the pkey_pckmo
implementation of the key_to_protkey() handler function. The handler
function fails, if the generated output data exceeds the length of the
provided target buffer.

The Linux kernel CVE team has assigned CVE-2026-64558 to this issue.


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

	Issue introduced in 6.12 with commit 8fcc231ce3bea12b78bb94b280cdc03cff342435 and fixed in 6.12.97 with commit 02028a24e26d85262ab9c8fc4344e1f3503007fc
	Issue introduced in 6.12 with commit 8fcc231ce3bea12b78bb94b280cdc03cff342435 and fixed in 6.18.40 with commit 433e5e70cdc1edf382d28d08a885b22e2b98b7da
	Issue introduced in 6.12 with commit 8fcc231ce3bea12b78bb94b280cdc03cff342435 and fixed in 7.1.5 with commit 614aa0491c7a190556c2345dddee0b6f5ed90989
	Issue introduced in 6.12 with commit 8fcc231ce3bea12b78bb94b280cdc03cff342435 and fixed in 7.2-rc1 with commit 1ac287e2af9a9112fe271427ef45eceb26bce8b4

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-2026-64558
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/s390/crypto/pkey_pckmo.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/02028a24e26d85262ab9c8fc4344e1f3503007fc
	https://git.kernel.org/stable/c/433e5e70cdc1edf382d28d08a885b22e2b98b7da
	https://git.kernel.org/stable/c/614aa0491c7a190556c2345dddee0b6f5ed90989
	https://git.kernel.org/stable/c/1ac287e2af9a9112fe271427ef45eceb26bce8b4