Bug 2559838 (CVE-2026-99003)

Summary:	CVE-2026-99003 kernel: drm/panthor: validate userspace queue count against initialized firmware slot count
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	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 Panthor Direct Rendering Manager (DRM) driver. When the hardware firmware initializes fewer queue slots than the driver's hardcoded maximum, the driver fails to properly validate the requested queue count against the actual initialized firmware slots. A local unprivileged attacker could exploit this flaw by submitting a request with more queues than supported by the firmware, leading to an uninitialized memory dereference, a system crash, and 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 2026-10-23 13:52:15 UTC

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

drm/panthor: validate userspace queue count against initialized firmware slot count

In panthor_drv.c:panthor_ioctl_group_create(),
the queue count is validated against the hardcoded maximum:

	if (!args->queues.count || args->queues.count > MAX_CS_PER_CSG)
		return -EINVAL;

However, if the firmware reports fewer slots than MAX_CS_PER_CSG,
panthor_fw_init_ifaces() will only initialize that smaller number of
stream interfaces.

If unprivileged userspace requests more queues than the firmware reported
(but no more than MAX_CS_PER_CSG), cs_slot_prog_locked() fetches an
uninitialized stream interface and may crash when dereferencing
cs_iface->input->ringbuf_base.

Comment 1 gkamathe 2026-10-28 05:44:57 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-99003.mbox