Bug 2536267 (CVE-2026-90102)

Summary:	CVE-2026-90102 kernel: NFSv4/pnfs: key the data server cache on the NFS version
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 the Linux kernel's NFSv4/pnfs component. The data server cache is incorrectly keyed only on the multipath address set, without considering the NFS version. This oversight allows different NFS versions to share the same internal data structure when two device IDs on one address have different NFS versions. A remote attacker could exploit this by configuring specific NFSv3 and NFSv4 device IDs on the same address, leading to a null pointer dereference and a system crash, 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 2026-09-17 17:13:02 UTC

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

NFSv4/pnfs: key the data server cache on the NFS version

nfs4_pnfs_ds_add() keys the per-net data server cache on the multipath
address set alone, and struct nfs4_pnfs_ds records no version. That
suffices for the files layout driver, which always connects with version
4, but flexfiles takes its version tuple from GETDEVICEINFO per device,
and one address can legitimately serve both NFSv3 and NFSv4.

Two deviceids on one address with different ds_versions[0].version
therefore share a single nfs4_pnfs_ds, and whichever mirror connects
first pins ds_clp to its own version. The other one is handed that
client anyway, so it selects rpc_call_ops for a version the connection
does not speak, and the mismatched sequence-slot handling dereferences
NULL.

Add the version to the cache key so the two cannot alias, giving each
version its own nfs4_pnfs_ds and connection while both mirrors stay
usable. Only the major version is compared, since that is what selects
rpc_call_ops and rpc_ops; v4.0 and v4.1 keep sharing a client. The files
layout driver passes the 4 it already hardcodes at connect time.

Comment 1 Keith Grant 2026-09-22 21:44:21 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90102.mbox