Bug 2535407 (CVE-2026-90021)

Summary:	CVE-2026-90021 kernel: usb: gadget: f_midi: initialize work in f_midi_alloc()
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability-draft	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
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's USB MIDI gadget driver (f_midi). When a sound card is not registered, a work queue item may not be properly initialized. This can lead to a warning and a potential system crash, resulting in a Denial of Service (DoS) for a local attacker.	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 12:45:51 UTC

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

usb: gadget: f_midi: initialize work in f_midi_alloc()

f_midi_alloc initializes free_ref to 1 and it can only be incremented
when a sound card is registered via f_midi_register_card().
f_midi_register_card() is only called in f_midi_bind() which actually
performs INIT_WORK. If f_midi_bind() is never run, work is not
initialized and the if condition in f_midi_free becomes true,
this results in a warning later in __flush_work as work->func = 0.
Fix this by moving INIT_WORK from f_midi_bind() to f_midi_alloc().

Comment 1 Mauro Matteo Cascella 2026-09-17 09:01:07 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90021.mbox