CVE-2026-80921: KVM: s390: vsie: zero stale crypto bits

CVE-2026-80921: KVM: s390: vsie: zero stale crypto bits

[Greg Kroah-Hartman]

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

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

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

KVM: s390: vsie: zero stale crypto bits

When shadowing crypto access bits from a format0 apcb (crycb 0 or 1),
the bits 64..255 are unchanged from whatever is in the vsie page in the
crycb and thus in the apcb. This gives a nested guest potential access
to a device no longer available. Zero out the remaining bits.

The Linux kernel CVE team has assigned CVE-2026-80921 to this issue.


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

	Issue introduced in 4.20 with commit 6b79de4b056e5a2febc0c61233d8f0ad7868e49c and fixed in 5.10.269 with commit d110b3297f11ef227098b8a82ade2d5f123b7d2f
	Issue introduced in 4.20 with commit 6b79de4b056e5a2febc0c61233d8f0ad7868e49c and fixed in 5.15.220 with commit 59d51550b5cb916bda037673a721a404b3b47a0d
	Issue introduced in 4.20 with commit 6b79de4b056e5a2febc0c61233d8f0ad7868e49c and fixed in 6.1.187 with commit f6079dca67eccb5eabef9f72437948c66dc5131f
	Issue introduced in 4.20 with commit 6b79de4b056e5a2febc0c61233d8f0ad7868e49c and fixed in 6.6.156 with commit 087c19cc60a8caa1a08e1e434c8be2caf6c27733
	Issue introduced in 4.20 with commit 6b79de4b056e5a2febc0c61233d8f0ad7868e49c and fixed in 6.12.108 with commit 7d23489f51109e3ebba5b5db8c5f0185af7b7fdf
	Issue introduced in 4.20 with commit 6b79de4b056e5a2febc0c61233d8f0ad7868e49c and fixed in 6.18.49 with commit 935eeba276012916c76243e5cbb843efd8fdb75d
	Issue introduced in 4.20 with commit 6b79de4b056e5a2febc0c61233d8f0ad7868e49c and fixed in 7.1.13 with commit d4bcd2df6d0d2af916b4fe1a533958778ea7c45b
	Issue introduced in 4.20 with commit 6b79de4b056e5a2febc0c61233d8f0ad7868e49c and fixed in 7.2.3 with commit 29b4f7bc2991313bd3e6f6fb8fdf1b173f086dd6
	Issue introduced in 4.20 with commit 6b79de4b056e5a2febc0c61233d8f0ad7868e49c and fixed in 7.3-rc1 with commit 34d5b5b646c91cfb9338d7a12c955a70ffb8c66b

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-2026-80921
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/vsie.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/d110b3297f11ef227098b8a82ade2d5f123b7d2f
	https://git.kernel.org/stable/c/59d51550b5cb916bda037673a721a404b3b47a0d
	https://git.kernel.org/stable/c/f6079dca67eccb5eabef9f72437948c66dc5131f
	https://git.kernel.org/stable/c/087c19cc60a8caa1a08e1e434c8be2caf6c27733
	https://git.kernel.org/stable/c/7d23489f51109e3ebba5b5db8c5f0185af7b7fdf
	https://git.kernel.org/stable/c/935eeba276012916c76243e5cbb843efd8fdb75d
	https://git.kernel.org/stable/c/d4bcd2df6d0d2af916b4fe1a533958778ea7c45b
	https://git.kernel.org/stable/c/29b4f7bc2991313bd3e6f6fb8fdf1b173f086dd6
	https://git.kernel.org/stable/c/34d5b5b646c91cfb9338d7a12c955a70ffb8c66b