Bug 2546487 (CVE-2026-98364)

Summary:	CVE-2026-98364 kernel: xfrm: hold net_device reference under RCU in bundle creation
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
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 IPsec (XFRM) networking subsystem. A race condition occurs when creating policy bundles while a network device is concurrently removed, leading to a use-after-free condition where the kernel accesses already-freed device memory. A local attacker can exploit this flaw to potentially escalate privileges or cause a Denial of Service (DoS) by crashing 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 2026-10-06 09:30:27 UTC

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

xfrm: hold net_device reference under RCU in bundle creation

xfrm_bundle_create() and xfrm_create_dummy_bundle() read dst->dev into
a local pointer without taking a device reference, then pass it to
xfrm_fill_dst(). A concurrent RTM_DELLINK replaces dst->dev via
dst_dev_put() and frees the old net_device, causing a use-after-free
when xfrm6_fill_dst() later dereferences the stale dev pointer.

  BUG: KASAN: slab-use-after-free in xfrm6_fill_dst+0x82c/0x860
  (net/ipv6/xfrm6_policy.c:86 netdev_hold())
  Read of size 8 at addr ffff8880142fe588 by task exploit/153
  Call Trace:
   xfrm6_fill_dst+0x82c/0x860
   xfrm_resolve_and_create_bundle+0x21d4/0x2bd0
   xfrm_lookup_with_ifid+0x485/0x1640
   ip6_dst_lookup_flow+0x19b/0x1e0
   udpv6_sendmsg+0x1443/0x2dd0

Fix this by reading dst->dev via dst_dev_rcu() and keeping the RCU
read-side critical section active until xfrm_fill_dst() has taken the
required device references.