Bug 2502441 (CVE-2026-64004)

Summary:	CVE-2026-64004 kernel: net/iucv: fix locking in .getsockopt
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:	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 AF_IUCV (Inter-User Communication Vehicle) networking module. A local user can exploit a race condition between message reception and socket option retrieval, specifically when calling getsockopt(SO_MSGSIZE). This can lead to a null pointer dereference, causing the kernel to crash and resulting in 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 2026-07-19 16:08:19 UTC

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

net/iucv: fix locking in .getsockopt

Mirror iucv_sock_setsockopt() and wrap the whole switch in
lock_sock()/release_sock(). The pre-existing SO_MSGLIMIT-only lock
becomes redundant and is removed.

Any AF_IUCV HIPER user can potentially crash the kernel by racing
recvmsg() with getsockopt(SO_MSGSIZE): the SO_MSGSIZE arm dereferences
iucv->hs_dev->mtu after iucv_sock_close() (called from the racing
recvmsg()) has set hs_dev to NULL, producing a NULL pointer dereference
oops.

Comment 1 Mauro Matteo Cascella 2026-07-21 15:02:36 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071907-CVE-2026-64004-7455@gregkh/T