Bug 2439868 (CVE-2026-23138)

Summary:	CVE-2026-23138 kernel: tracing: Add recursion protection in kernel stack trace recording
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	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in the Linux kernel's tracing subsystem. When tracing RCU events with the kernel stack trace trigger enabled, an infinite recursion can occur because the stack trace recording code calls back into RCU, which then triggers another stack trace. This leads to a stack overflow and kernel crash.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-02-14 16:02:32 UTC

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

tracing: Add recursion protection in kernel stack trace recording

A bug was reported about an infinite recursion caused by tracing the rcu
events with the kernel stack trace trigger enabled. The stack trace code
called back into RCU which then called the stack trace again.

Expand the ftrace recursion protection to add a set of bits to protect
events from recursion. Each bit represents the context that the event is
in (normal, softirq, interrupt and NMI).

Have the stack trace code use the interrupt context to protect against
recursion.

Note, the bug showed an issue in both the RCU code as well as the tracing
stacktrace code. This only handles the tracing stack trace side of the
bug. The RCU fix will be handled separately.

Comment 1 Alexander B 2026-02-16 12:42:13 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026021429-CVE-2026-23138-9853@gregkh/T