Bug 2536229 (CVE-2026-93172)

Summary:	CVE-2026-93172 kernel: mm/mm_init: handle alloc_percpu failure in free_area_init_core_hotplug
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
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 memory management (mm/mm_init). A missing allocation check for pgdat->per_cpu_nodestats can lead to a NULL dereference. This vulnerability could allow a local attacker to cause a system crash, resulting in a Denial of Service (DoS).	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 2026-09-17 17:00:40 UTC

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

mm/mm_init: handle alloc_percpu failure in free_area_init_core_hotplug

We miss a failed allocation check for pgdat->per_cpu_nodestats, which
results in a NULL deref when we offset into the per-cpu area.

Propagate -ENOMEM up the stack and leave per_cpu_nodestats pointing
at boot_nodestats so a later online can retry the allocation.

hotadd_init_pgdat() returns NULL on failure, which __try_online_node()
already maps to -ENOMEM.

On failure nothing needs to be unwound:
  - the node is never marked online
  - per_cpu_nodestats is left pointing at boot_nodestats
  - __add_memory_resource() cleans up pending memblock resources
  - later online attempts retry the per_cpu_nodestats allocation

Comment 1 gkamathe 2026-09-18 05:26:55 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93172.mbox