Bug 2555034 (CVE-2026-98574)

Summary:	CVE-2026-98574 kernel: net: bcmgenet: stop Tx NAPI before disabling the queues
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 Broadcom GENET network driver. Improper synchronization between disabling transmission queues and stopping completion polling during interface shutdown or suspend operations can prematurely re-enable a queue. This race condition allows packet transmission to access freed memory buffers, causing a use-after-free condition. A local user could exploit this issue during device reconfiguration to trigger memory corruption, leading to a Denial of Service (DoS) via a system crash.	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 2026-10-18 15:40:36 UTC

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

net: bcmgenet: stop Tx NAPI before disabling the queues

bcmgenet_netif_stop() and the Wake-on-LAN branch of bcmgenet_suspend()
both disable the Tx queues first and stop Tx NAPI several steps later. A
completion in flight calls netif_tx_wake_queue() in between, and nothing
stops the queue again, so a transmit can reach the rings after they have
been freed.

Close is safe because dev_deactivate_many() stops the qdisc first.
bcmgenet_suspend() does not, so stop Tx NAPI before the queues on both
paths.

KASAN on a Raspberry Pi CM4, driven from an MTU change because suspend
freezes user space before the callback runs:

  BUG: KASAN: use-after-free in bcmgenet_xmit+0x17f8/0x2258
  Write of size 8 at addr ffffff8055844a68 by task ksoftirqd/0/14
   bcmgenet_xmit+0x17f8/0x2258
   dev_hard_start_xmit+0x13c/0x588
   sch_direct_xmit+0x108/0x340
   __dev_queue_xmit+0x1190/0x3848