Bug 2536787 (CVE-2026-90104)

Summary:	CVE-2026-90104 kernel: NFSv4.1: zero referring call lists before decoding
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
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Doc Text:	A flaw was found in the Linux kernel's NFSv4.1 implementation. When decoding callback sequence arguments, an uninitialized pointer in the `referring_call_list` can be passed to the `kfree()` function. This memory corruption vulnerability could allow a remote attacker to cause a denial of service by triggering the flaw during NFSv4.1 operations.	Story Points:	---
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Last Closed:		Type:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 19:33:13 UTC

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

NFSv4.1: zero referring call lists before decoding

decode_cb_sequence_args() allocates csa_rclists with kmalloc_objs(), so
each referring_call_list starts uninitialized. decode_rc_list() assigns
rcl_refcalls only when rcl_nrefcalls is nonzero. A valid list with zero
referring calls therefore leaves the pointer uninitialized, and
nfs4_callback_sequence() later passes stale slab contents to kfree().

Allocate csa_rclists with kzalloc_objs() so every rcl_refcalls member is
NULL from the beginning, including valid empty referring call lists.

Comment 1 Keith Grant 2026-09-22 22:03:12 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90104.mbox