Bug 2535220 (CVE-2026-89959)

Summary:	CVE-2026-89959 kernel: s390/vfio-ap: Fix control domain removal in vfio_ap_mdev_cfg_remove
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in the Linux kernel's s390/vfio-ap component. An incorrect function was used during the removal of control domains, specifically `bitmap_andnot` instead of `bitmap_and`. This error prevents explicitly unplugged control domains from being properly removed from a Kernel-based Virtual Machine (KVM) guest. This could lead to improper resource management and unexpected behavior within virtualized environments.	Story Points:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-16 11:37:21 UTC

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

s390/vfio-ap: Fix control domain removal in vfio_ap_mdev_cfg_remove

The vfio_ap_config_remove function uses the bitmap_andnot function to clear
bits from the matrix_mdev->matrix.adm bitmap (specifies the control domains
assigned to the mdev). This prevents the explicitly unplugged control
domains from being removed the KVM guest. The bitmap_and function is used
instead.

Comment 1 Keith Grant 2026-09-16 18:34:25 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89959.mbox