Bug 2535372 (CVE-2026-89922)

Summary: CVE-2026-89922 kernel: KVM: s390: Take srcu when importing watchpoint data
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: 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 Kernel-based Virtual Machine (KVM) for the s390 architecture within the Linux kernel. A concurrency issue exists in the `__import_wp_info()` function when importing watchpoint data. If a memory slot update occurs concurrently without the required locks being held, the memory slot array can be prematurely freed. This could lead to memory corruption, potentially causing system instability or a denial of service.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-16 12:23:13 UTC 
In the Linux kernel, the following vulnerability has been resolved:

KVM: s390: Take srcu when importing watchpoint data

__import_wp_info() backs up the original guest memory contents of a
watchpoint with read_guest_abs(), which is kvm_read_guest() and therefore
resolves the memslot via __kvm_memslots(). That requires kvm->srcu (or
kvm->slots_lock) to be held, otherwise a concurrent memslot update can
free the memslots array under us once its SRCU grace period has elapsed.

As this is not fast path, following lock ordering (mutex first, then
srcu) take the big hammer and hold the srcu for the full import.
Comment 1 Keith Grant 2026-09-22 12:29:55 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89922.mbox