Bug 2555211 (CVE-2026-98868)

Summary:	CVE-2026-98868 kernel: dm-pcache: reject a kset that overruns its segment
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 dm-pcache driver. A local attacker capable of presenting a crafted storage device with forged metadata can cause cache operations to exceed segment boundaries. This flaw triggers a kernel assertion failure, leading to a system crash and 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 2026-10-18 16:02:10 UTC

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

dm-pcache: reject a kset that overruns its segment

cache_replay(), the writeback worker and the GC worker read a kset of
get_kset_onmedia_size() bytes and advance the position by it. A forged
key_num makes that size exceed the segment's remaining space, so the
advance walks past the segment and trips the cache_pos_advance() BUG_ON.

Reject a kset whose on-media size exceeds cache_seg_remain() before use.

Comment 1 gkamathe 2026-10-24 07:24:23 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98868.mbox