linux-cve-announce - CVE-2025-68333: sched_ext: Fix possible deadlock in the deferred_irq

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Message-ID: <2025122219-CVE-2025-68333-4689@gregkh>
Date: Mon, 22 Dec 2025 17:14:25 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68333: sched_ext: Fix possible deadlock in the deferred_irq_workfn()

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

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

sched_ext: Fix possible deadlock in the deferred_irq_workfn()

For PREEMPT_RT=y kernels, the deferred_irq_workfn() is executed in
the per-cpu irq_work/* task context and not disable-irq, if the rq
returned by container_of() is current CPU's rq, the following scenarios
may occur:

lock(&rq->__lock);
<Interrupt>
  lock(&rq->__lock);

This commit use IRQ_WORK_INIT_HARD() to replace init_irq_work() to
initialize rq->scx.deferred_irq_work, make the deferred_irq_workfn()
is always invoked in hard-irq context.

The Linux kernel CVE team has assigned CVE-2025-68333 to this issue.


Affected and fixed versions
===========================

	Fixed in 6.17.12 with commit 600b4379b9a7ba41340d652211fb29699da4c629
	Fixed in 6.18 with commit a257e974210320ede524f340ffe16bf4bf0dda1e

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-68333
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	kernel/sched/ext.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/600b4379b9a7ba41340d652211fb29699da4c629
	https://git.kernel.org/stable/c/a257e974210320ede524f340ffe16bf4bf0dda1e