Bug 2536297 (CVE-2026-93198)

Summary:	CVE-2026-93198 kernel: dm-pcache: validate the persisted dirty_tail chain at load
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 component. A local attacker could provide a specially crafted image with a malformed dirty_tail chain. This could cause the writeback worker to enter an infinite loop, leading to a denial of service (DoS) condition on the system.	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 17:16:52 UTC

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

dm-pcache: validate the persisted dirty_tail chain at load

The writeback worker follows the persisted dirty_tail chain, which is
decoded from the cache device independently of the key_tail chain that
cache_replay() walks and bounds. A crafted image, whose on-media fields are
authenticated only by a crc32c with a fixed seed, can aim dirty_tail at a
chain of last ksets that never terminates, so cache_writeback_fn() re-arms
itself with no delay forever.

Walk the dirty_tail chain once at load with the same hop cap cache_replay()
uses and fail the table load with -EIO if it does not reach an end within
n_segs hops.

Comment 1 gkamathe 2026-09-18 09:38:51 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93198.mbox