Bug 2532510 (CVE-2026-89570)

Summary:	CVE-2026-89570 kernel: cxl/mce: Make the MCE notifier per-region
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 Compute Express Link (CXL) subsystem. Lifetime issues with the CXL Machine Check Exception (MCE) notifier can lead to NULL dereferences and use-after-free vulnerabilities in the MCE handler. This could allow an attacker to cause 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 2026-09-11 23:34:32 UTC

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

cxl/mce: Make the MCE notifier per-region

Flavien Solt reported lifetime issues with the CXL MCE notifier, which
can lead to NULL dereferences and use-after-free in the MCE handler.
The notifier was registered per memory device and stored in 'struct
cxl_memdev_state', even though it only needs the region state (the
region's SPA range and its extended linear cache size).

Instead of keeping the memory device and endpoint alive, the correct fix
is to move the notifier into 'struct cxl_region' and register it from
cxl_region_probe() as it should be a per-region notifier. Setup the
registration to only happen for regions that have an extended linear
cache as that is the only current usage.

Remove cxl_port_get_spa_cache_alias() as it is now dead code.

[ dj: Update dev_warn() when notifier fails due to kconfig. (Ben) ]

Comment 1 gkamathe 2026-09-15 06:17:41 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89570.mbox