Bug 2536213 (CVE-2026-90164)

Summary:	CVE-2026-90164 kernel: smb/server: abort initialization when proc setup fails
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 ksmbd server component. During the server's initialization process, an error in setting up internal process entries or counters is not handled correctly. This oversight can result in the system attempting to access a null pointer, which may lead to a system crash or a denial of service (DoS). Furthermore, this issue could leave behind unremovable entries in the system's /proc filesystem, exacerbating resource management problems.	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 16:54:29 UTC

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

smb/server: abort initialization when proc setup fails

ksmbd_server_init() calls ksmbd_proc_init() before creating the
remaining proc entries and server subsystems. ksmbd_proc_init() tears
down partial state on a procfs or percpu_counter allocation failure,
but returns void, so ksmbd_server_init() continues as if the counters
were usable.

Once userspace starts the server, server_ctrl_handle_init() calls
ksmbd_proc_reset(), which reaches percpu_counter_set() with a NULL
per-CPU counters pointer on SMP systems. The later ksmbd_proc_create()
calls also receive a NULL parent and may create entries in the /proc
root; ksmbd_proc_cleanup() cannot remove those entries because
ksmbd_proc_fs is NULL.