Bug 2555223 (CVE-2026-98831)

Summary:	CVE-2026-98831 kernel: of/overlay: don't leak fragment references when changeset init fails
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 Device Tree overlay subsystem. This flaw allows a local user to cause a Denial of Service (DoS) through memory exhaustion. When an overlay changeset fails during target or symbol lookup, the kernel fails to release previously acquired fragment references during error cleanup. By repeatedly triggering this initialization failure, an attacker can leak kernel memory over time.	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 2026-10-18 16:02:56 UTC

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

of/overlay: don't leak fragment references when changeset init fails

init_overlay_changeset() stores the number of initialized fragments
in ovcs->count only on full success. When find_target() or the
__symbols__ lookup fails partway through, the target and overlay
references taken for the fragments initialized so far are never
dropped: free_overlay_changeset() bounds its cleanup loop by
ovcs->count, which is still 0.

Store the running count on the error path so free_overlay_changeset()
puts whatever was set up. The store is guarded by ovcs->fragments
because on the allocation-failure path cnt still holds the counting
pass total while there is no fragments array; everywhere else cnt
only counts fully-initialized fragments.

Comment 1 Mauro Matteo Cascella 2026-10-23 20:50:31 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98831.mbox