Bug 2532110 (CVE-2026-89484)

Summary:	CVE-2026-89484 kernel: lockd: fix NULL dereference on lockowner allocation failure
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
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 `lockd` component. This vulnerability occurs when the Network Lock Manager (NLM) client attempts to initialize file lock operations without successfully allocating a lockowner. This can lead to a NULL pointer dereference during the release of the file lock, resulting in a system crash. An attacker could potentially exploit this to cause a denial of service.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-11 20:43:18 UTC

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

lockd: fix NULL dereference on lockowner allocation failure

nlmclnt_locks_init_private() installs NLM file lock operations even when
nlmclnt_find_lockowner() fails to allocate a lockowner. nlmclnt_proc()
then returns -ENOMEM, but the VFS still tears down the partially
initialized file_lock and calls locks_release_private().

That invokes nlmclnt_locks_release_private(), which dereferences
fl->fl_u.nfs_fl.owner and crashes because the owner was never installed.

Clear fl_ops before attempting to initialize the NLM private state, and
install the NLM lock operations only after a lockowner has been allocated
successfully.

Comment 1 Mauro Matteo Cascella 2026-09-18 09:56:41 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89484.mbox