CVE-2026-72290: KVM: s390: pci: Fix GISC refcount leak on AIF enable failure

CVE-2026-72290: KVM: s390: pci: Fix GISC refcount leak on AIF enable failure

[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 GISC refcount leak on AIF enable failure

kvm_s390_gisc_register() registers the guest ISC before pinning
the guest interrupt forwarding pages and allocating the AISB bit.
If any of the later setup steps fails, the function unwinds the
pinned pages and other local state, but does not unregister the
GISC reference. Add the missing kvm_s390_gisc_unregister() to the
error unwind path.

The Linux kernel CVE team has assigned CVE-2026-72290 to this issue.


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

	Issue introduced in 6.0 with commit 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc and fixed in 6.1.178 with commit 3882224b0e714f34de91e5f28307c5d3fccfe8f8
	Issue introduced in 6.0 with commit 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc and fixed in 6.6.145 with commit 6e69317cd44a2f21f8f7a9d93eb3220e868adfa8
	Issue introduced in 6.0 with commit 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc and fixed in 6.12.97 with commit 6cd6e1c978784eec9032e2fe94a53e62b674fe3e
	Issue introduced in 6.0 with commit 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc and fixed in 6.18.40 with commit 5fb75c5272950b3ebe8bdee7abfdafd44f38313b
	Issue introduced in 6.0 with commit 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc and fixed in 7.1.5 with commit adce12bb0e0dc82d1d6f0821c9faee3145e62a6f
	Issue introduced in 6.0 with commit 3c5a1b6f0a18520a0edd0600fef6f1a8553b8fdc and fixed in 7.2-rc4 with commit 7b69729046a4c58f4cb457184e5ac4aaa179bff4

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-2026-72290
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/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/3882224b0e714f34de91e5f28307c5d3fccfe8f8
	https://git.kernel.org/stable/c/6e69317cd44a2f21f8f7a9d93eb3220e868adfa8
	https://git.kernel.org/stable/c/6cd6e1c978784eec9032e2fe94a53e62b674fe3e
	https://git.kernel.org/stable/c/5fb75c5272950b3ebe8bdee7abfdafd44f38313b
	https://git.kernel.org/stable/c/adce12bb0e0dc82d1d6f0821c9faee3145e62a6f
	https://git.kernel.org/stable/c/7b69729046a4c58f4cb457184e5ac4aaa179bff4