Bug 2540492 (CVE-2026-93804)

Summary:	CVE-2026-93804 kernel: wifi: mac80211: ibss: wait for in-flight TX on disconnect
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 mac80211 wireless subsystem. A race condition can occur when disconnecting from an Independent Basic Service Set (IBSS, an ad-hoc wireless network) while network traffic is simultaneously being transmitted across processor cores. This timing conflict causes data packets to reach the wireless driver after disconnection has initiated, which may trigger driver instability and lead to a Denial of Service (DoS) or 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 2026-09-24 17:00:26 UTC

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

wifi: mac80211: ibss: wait for in-flight TX on disconnect

While leaving an IBSS in ieee80211_ibss_disconnect() mac80211 flushes
stations, turns the carrier off and immediately tells the driver to
leave as well. While there may be synchronize_net() in station flush
and in this code later, packets can still be transmitted due to
cross-CPU race conditions after carrier off is set.
Therefore, it's possible for a race to happen where a TX to the
driver occurs while or after telling it to leave the IBSS. This can
be confusing to drivers, and in the case of iwlwifi leads to an
attempt to use invalid queues.

Move netif_carrier_off() to occur before sta_info_flush() during
IBSS disconnect, and add synchronize_net() if flushing didn't,
so that the synchronize_net() always happens between turning the
carrier off and telling the driver, avoiding this race.

Comment 1 Mauro Matteo Cascella 2026-09-28 12:36:02 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93804.mbox