Bug 2536749 (CVE-2026-93081)

Summary:	CVE-2026-93081 kernel: firmware: arm_scmi: Fix SCMI device destroy lifetimes
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 ARM System Control and Management Interface (SCMI) firmware. This vulnerability occurs due to improper handling of device reference counts during the device destruction process. A concurrent unregister operation can release a device while its pointer is still in use, leading to a use-after-free condition. This can result in system instability or 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 19:24:55 UTC

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

firmware: arm_scmi: Fix SCMI device destroy lifetimes

scmi_child_dev_find() drops the reference returned by
device_find_child() before returning the scmi_device pointer. A
concurrent unregister can then release the device while the destroy path
is still using the returned pointer.

Make the lookup helper return the device_find_child() reference and keep
it until scmi_device_destroy() has finished unregistering the child.

Also split device_unregister() in __scmi_device_destroy() so the SCMI bus
ID is not made reusable until after device_del() has removed the old
scmi_dev.N name from sysfs. This avoids a new SCMI device reusing the
same ID while the old device is still registered.

The final device release callback is also a possible cleanup path when
SCMI children are deleted by driver core recursion rather than
__scmi_device_destroy(). Release the SCMI bus ID from a common helper
used by destroy, register-failure and final-release paths, and clear
scmi_dev->id after freeing it so the final release cannot free the same
ID again.

Comment 1 gkamathe 2026-09-19 23:31:36 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93081.mbox