CVE-2026-52968: KVM: s390: pci: fix GAIT table indexing due to double-scaling pointer arithmetic

CVE-2026-52968: KVM: s390: pci: fix GAIT table indexing due to double-scaling pointer arithmetic

[Greg Kroah-Hartman]

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

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

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

KVM: s390: pci: fix GAIT table indexing due to double-scaling pointer arithmetic

kvm_s390_pci_aif_enable(), kvm_s390_pci_aif_disable(), and
aen_host_forward() index the GAIT by manually multiplying the index
with sizeof(struct zpci_gaite).

Since aift->gait is already a struct zpci_gaite pointer, this
double-scales the offset, accessing element aisb*16 instead of aisb.

This causes out-of-bounds accesses when aisb >= 32 (with
ZPCI_NR_DEVICES=512)

Fix by removing the erroneous sizeof multiplication.

The Linux kernel CVE team has assigned CVE-2026-52968 to this issue.


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

	Issue introduced in 6.0 with commit 73f91b004321f2510fa79e66035dbbf1870fcf56 and fixed in 6.1.175 with commit 31a9d9f9942885aae356a1a57c79e82c5b5b0828
	Issue introduced in 6.0 with commit 73f91b004321f2510fa79e66035dbbf1870fcf56 and fixed in 6.6.141 with commit a99a25db131ece5e6c0f7632da606de631efe4f2
	Issue introduced in 6.0 with commit 73f91b004321f2510fa79e66035dbbf1870fcf56 and fixed in 6.12.91 with commit 11b8ff5b930b351dd1f6f088dce0beb027ac92d0
	Issue introduced in 6.0 with commit 73f91b004321f2510fa79e66035dbbf1870fcf56 and fixed in 6.18.33 with commit b22a2da8792a7bfe743c1a922e77fa499ddedbe8
	Issue introduced in 6.0 with commit 73f91b004321f2510fa79e66035dbbf1870fcf56 and fixed in 7.0.10 with commit e7216651b94e92e5433fb2f54b77864642b4ea48
	Issue introduced in 6.0 with commit 73f91b004321f2510fa79e66035dbbf1870fcf56 and fixed in 7.1 with commit 16d990a15491cf76cd6eef0846e1b4100e63261a

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-2026-52968
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/kvm/interrupt.c
	arch/s390/kvm/pci.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/31a9d9f9942885aae356a1a57c79e82c5b5b0828
	https://git.kernel.org/stable/c/a99a25db131ece5e6c0f7632da606de631efe4f2
	https://git.kernel.org/stable/c/11b8ff5b930b351dd1f6f088dce0beb027ac92d0
	https://git.kernel.org/stable/c/b22a2da8792a7bfe743c1a922e77fa499ddedbe8
	https://git.kernel.org/stable/c/e7216651b94e92e5433fb2f54b77864642b4ea48
	https://git.kernel.org/stable/c/16d990a15491cf76cd6eef0846e1b4100e63261a