Bug 2540388 (CVE-2026-97489)

Summary:	CVE-2026-97489 kernel: bfs: handle set_blocksize failures
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 BFS (Boot File System) implementation. The kernel fails to properly verify the return value when setting the block size during a mount operation. A local user with permissions to mount file systems could exploit this issue by mounting an incompatible file system image, causing a kernel 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 2026-09-24 16:38:10 UTC

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

bfs: handle set_blocksize failures

bfs uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting will hit the

	BUG_ON(offset >= folio_size(folio));

in folio_set_bh on the first __bread_gfp call.

Comment 1 Mauro Matteo Cascella 2026-09-29 20:24:04 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97489.mbox