Bug 2536469 (CVE-2026-90418)

Summary:	CVE-2026-90418 kernel: nilfs2: fix BUG in nilfs_copy_dirty_pages() on dirty state mismatch
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
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 nilfs2, a file system in the Linux kernel. This vulnerability occurs when a dirty page unexpectedly loses its dirty status during a copy operation, particularly after the filesystem detects metadata corruption and transitions to read-only mode. An attacker could potentially trigger a kernel bug, leading to a system crash and a denial of service.	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 18:05:51 UTC

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

nilfs2: fix BUG in nilfs_copy_dirty_pages() on dirty state mismatch

Syzbot reported a kernel BUG triggered within nilfs_copy_dirty_pages(),
which copies dirty DAT file folios/pages to its shadow page cache.  The
BUG occurs when a retrieved dirty folio/page unexpectedly loses its
'dirty' status.

This issue arises because, since the commit referenced below, the 'dirty'
flag of a folio/page can be cleared asynchronously after the filesystem
detects metadata corruption and transitions to read-only mode.

Resolve the issue by returning an -EROFS error if the filesystem has
transitioned to read-only mode.  Also change the behavior to issue a
kernel warning only once instead of triggering a kernel BUG when this
unexpected 'dirty' state is detected while the filesystem is not in
read-only mode.

Comment 1 gkamathe 2026-09-21 12:35:56 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90418.mbox