Bug 2528785 (CVE-2026-80891)

Summary:	CVE-2026-80891 kernel: KVM: s390: pci: Validate AIBV and AISB before pinning guest pages
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
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
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's KVM (Kernel-based Virtual Machine) s390 PCI component. This vulnerability arises from insufficient validation of the Adapter Interrupt Block Vector (AIBV) and Adapter Interrupt Summary Block (AISB) parameters before pinning guest pages. An attacker, by providing malformed AIBV or AISB values, could potentially cause the system to perform unsafe memory operations, leading to system instability or a denial of service.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
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Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-04 17:33:12 UTC

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

KVM: s390: pci: Validate AIBV and AISB before pinning guest pages

The AIBV holds one bit per MSI-X vector for a given function. The size of
the bit vector is derived from the NOI and the AIBVO. If the size of the
AIBV exceeds a single page boundary, then reject the request as we cannot
safely pin the guest AIBV.

Similarly reject the request if the AISB address is not 8-byte aligned as
the architecture requires doubleword alignment for the summary bit address.
Since the AISBO can address up to 64 bits, the size of the AISB can only be
8 bytes for the function. This also ensures the AISB doesn't exceed a
single page boundary.

Comment 1 Mauro Matteo Cascella 2026-09-07 09:51:35 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80891.mbox