Bug 2536718 (CVE-2026-90192)

Summary:	CVE-2026-90192 kernel: mailbox: qcom-cpucp: handle NULL data in send_data callback
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:	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 qcom-cpucp mailbox driver. The `qcom_cpucp_mbox_send_data()` function, responsible for sending data, did not properly handle a NULL data pointer when `mailbox_clear_channel()` attempted to notify the remote side that the receive (RX) channel was cleared. This blind dereferencing of a NULL pointer could lead to a kernel panic, effectively causing a Denial of Service (DoS) on 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 2026-09-17 19:17:53 UTC

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

mailbox: qcom-cpucp: handle NULL data in send_data callback

mailbox_clear_channel() calls mbox_send_message() with NULL data to
notify the remote side that the RX channel has been cleared.
qcom_cpucp_mbox_send_data() blindly dereferenced the data pointer,
causing a NULL pointer dereference kernel panic when invoked from
this path under PREEMPT_RT.

Add an explicit NULL check and return early without writing to the
TX register, which is the correct behaviour for a channel-clear
notification.

Comment 1 Keith Grant 2026-09-23 22:02:38 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90192.mbox