Bug 2535150 (CVE-2026-89874)

Summary:	CVE-2026-89874 kernel: media: v4l2-async: avoid deleting unlinked ASC entry on link error
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
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 v4l2-async media subsystem. When creating ancillary media links, the v4l2_async_match_notify() function attempts to delete an unlinked entry if the link creation fails. This can lead to a null pointer dereference, potentially causing a system crash. A local attacker could exploit this vulnerability to cause a Denial of Service.	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 2026-09-16 11:00:57 UTC

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

media: v4l2-async: avoid deleting unlinked ASC entry on link error

v4l2_async_match_notify() creates ancillary media links before adding
asc->asc_subdev_entry to sd->asc_list.

If ancillary link creation fails, the function jumps to
err_call_unbind while asc_subdev_entry has not been linked yet. Async
connections are zero-allocated, so the list entry still has NULL next
and prev pointers on this path. Calling list_del() on it can therefore
dereference NULL instead of returning the original link creation error.

Do not delete asc_subdev_entry from err_call_unbind. There is no list
insertion to undo on this path; the bound callback and sub-device
registration are the operations that need to be rolled back.

Comment 1 Mauro Matteo Cascella 2026-09-22 09:30:41 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89874.mbox