Bug 2536599 (CVE-2026-90318)

Summary:	CVE-2026-90318 kernel: fat: release buffer head after rebuilding parent
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 FAT (File Allocation Table) filesystem, specifically within the Network File System (NFS) export path. The `fat_rebuild_parent()` function fails to release a buffer head after successfully scanning a directory entry. This oversight can lead to a resource leak, potentially allowing a local attacker to cause a Denial of Service (DoS) by exhausting system resources.	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 18:39:39 UTC

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

fat: release buffer head after rebuilding parent

fat_scan_logstart() leaves the matching directory entry's buffer head in
sinfo.bh for the caller to release, just like fat_scan().

fat_rebuild_parent() uses the directory entry to rebuild the parent inode
for the nostale_ro NFS export path, but does not release sinfo.bh after a
successful scan.  Release it once fat_build_inode() has consumed the
directory entry data.

Comment 1 gkamathe 2026-09-23 07:58:08 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90318.mbox