Bug 2532318 (CVE-2026-89614)

Summary:	CVE-2026-89614 kernel: ntfs: bound the free-cluster bitmap scan to the volume
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 NTFS file system driver. This vulnerability occurs because the free-cluster bitmap scan is not properly bounded to the volume size. A specially crafted NTFS image, where the bitmap covers more clusters than the volume actually has, can lead to an out-of-bounds read when a file on such a volume is extended. This could result in system instability or the disclosure of sensitive information.	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 22:19:56 UTC

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

ntfs: bound the free-cluster bitmap scan to the volume

vol->lcn_empty_bits_per_page is sized from vol->nr_clusters at mount, but
ntfs_cluster_alloc() bounds its scan of that array by the size of $Bitmap.
Those are independent on-disk quantities and the mount-time check only
rejects a $Bitmap that is too small, so an image whose $Bitmap covers more
clusters than the volume has lets the scan index past the array.  A run
whose LCN lies in that gap takes the allocator straight there, since the
caller passes the file's own last LCN as its locality hint.  KASAN reports
a slab out-of-bounds read when a file on such a volume is extended.

Clamp the scan to what that array covers, mirroring the max_index
calculation the mount-time scan already uses, and reject a decoded LCN
at or beyond nr_clusters in the mapping pairs decoder.  Conforming
volumes are unaffected.