Bug 2536393 (CVE-2026-93091)

Summary: CVE-2026-93091 kernel: firmware: arm_scmi: Quiesce notifications before teardown
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: 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   
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A flaw was found in the arm_scmi firmware component of the Linux kernel. A race condition exists during the teardown of notifications or on the probe error path. This can allow an attacker to trigger a use-after-free vulnerability, where the system attempts to access memory that has already been released. The concrete consequence is a dereference of freed memory, which can lead to system instability or a denial of service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-17 17:42:39 UTC 
In the Linux kernel, the following vulnerability has been resolved:

firmware: arm_scmi: Quiesce notifications before teardown

scmi_notification_exit() clears and releases the notification instance,
but transport callbacks can still deliver incoming notifications until
the TX/RX channels are freed. During remove, an RX interrupt in that
window can enter scmi_notify() while notification state is being torn
down and then dereference freed memory. The same ordering exists on the
probe error path after notification initialization.

The notification late-init worker has a separate lifetime issue: protocol
event registration queues ni->init_work on the system workqueue, so
destroying ni->notify_wq does not drain that work. If the devres group is
released while init_work is still pending or running, the late-init worker
can dereference the freed notification instance.

Quiesce the notification core before TX/RX channels are torn down, then
clean up the channels before releasing the notification core resources.
Use disable_work_sync() so future late-init queueing is rejected and any
already queued or running late-init work has completed before channel
teardown starts.
Comment 1 gkamathe 2026-09-19 03:21:25 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93091.mbox