CVE-2026-80551: s390/vfio_ccw: Ensure first IDAW remains constant

CVE-2026-80551: s390/vfio_ccw: Ensure first IDAW remains constant

[Greg Kroah-Hartman]

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

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

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

s390/vfio_ccw: Ensure first IDAW remains constant

The first IDAW in a list does not need to be on a 2K/4K boundary
like all others, and so is read separately to accurately calculate
the size of the buffer needed to read the full IDAL.

Verify that the address found in the first IDAW is unchanged between
reads, to ensure a consistent set of IDAWs being worked with.

The Linux kernel CVE team has assigned CVE-2026-80551 to this issue.


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

	Issue introduced in 5.3 with commit 01aa26c672c0eb771de4aaa2a8ccf6055778887b and fixed in 6.12.105 with commit 0d46c2565f173bcddcdcaf44a4f69789a20535e2
	Issue introduced in 5.3 with commit 01aa26c672c0eb771de4aaa2a8ccf6055778887b and fixed in 6.18.46 with commit 08ef2a82115690d6e229615872ac1731af732497
	Issue introduced in 5.3 with commit 01aa26c672c0eb771de4aaa2a8ccf6055778887b and fixed in 7.1.10 with commit fc59e9482117ebdccd6dc7fa8082f8b980fd021e
	Issue introduced in 5.3 with commit 01aa26c672c0eb771de4aaa2a8ccf6055778887b and fixed in 7.2 with commit 565bef268d75bf7df665bce6923a88cd0eb74592

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-2026-80551
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/cio/vfio_ccw_cp.c
	drivers/s390/cio/vfio_ccw_cp.h


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/0d46c2565f173bcddcdcaf44a4f69789a20535e2
	https://git.kernel.org/stable/c/08ef2a82115690d6e229615872ac1731af732497
	https://git.kernel.org/stable/c/fc59e9482117ebdccd6dc7fa8082f8b980fd021e
	https://git.kernel.org/stable/c/565bef268d75bf7df665bce6923a88cd0eb74592