Bug 2507151 (CVE-2026-64291)

Summary:	CVE-2026-64291 kernel: iommufd: Set veventq_depth upper bound
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:	rhel-process-autobot, 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 iommufd subsystem. A local user could exploit this vulnerability by allocating excessively large event queues, leading to the exhaustion of kernel memory. This can result in a Denial of Service (DoS) for the system.	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 2026-07-25 10:07:43 UTC

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

iommufd: Set veventq_depth upper bound

iommufd_veventq_alloc() accepts any !0 veventq_depth from userspace, with
an upper bound at U32_MAX.

This leaves a vulnerability where userspace can allocate excessively large
queues to exhaust kernel memory reserves.

Cap the veventq_depth (maximum number of entries) to 1 << 19, matching the
maximum number of entries in the SMMUv3 EVTQ (the largest use case today).

Comment 1 TEJ RATHI 2026-07-29 15:29:20 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072504-CVE-2026-64291-7b0c@gregkh/T