From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-89519: sched_ext: Replace SCX_RQ_BAL_KEEP with a dispatch verdict return
Date: Fri, 11 Sep 2026 21:43:28 +0200 [thread overview]
Message-ID: <2026091114-CVE-2026-89519-b25f@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Replace SCX_RQ_BAL_KEEP with a dispatch verdict return
SCX_RQ_BAL_KEEP tells the pick to keep running the previous task, a leftover
from when balancing and picking were separate operations. An rq-level flag
only works while dispatches and picks pair up one to one, which core
scheduling breaks: selections interleave through dispatch's lock drops and a
pick can consume a stale flag, keeping a task that has since been dequeued.
Fixing core scheduling support requires the decision to travel with the
dispatch that made it. Make scx_dispatch_sched() and balance_one() return an
explicit verdict instead and drop the flag's plumbing from the tools autogen
enum headers.
Also factor the pick-side invocation, its follow-up queueing and the
post-dispatch checks out of do_pick_task_scx() into dispatch_pick(). No
functional changes intended.
v2: Drop the SCX_RQ_BAL_KEEP plumbing from the tools autogen enum headers
as well (Andrea).
The Linux kernel CVE team has assigned CVE-2026-89519 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.19 with commit 4c95380701f58b8112f0b891de8d160e4199e19d and fixed in 7.2.4 with commit 6f1d3bfe54430f8d54e0530a27f2ecbf8466576e
Issue introduced in 6.19 with commit 4c95380701f58b8112f0b891de8d160e4199e19d and fixed in 7.3-rc1 with commit ffaab58d217581cb75353168f8812a16e10463fc
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-2026-89519
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/ext.c
kernel/sched/sched.h
tools/sched_ext/include/scx/enum_defs.autogen.h
tools/sched_ext/include/scx/enums.autogen.bpf.h
tools/sched_ext/include/scx/enums.autogen.h
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/6f1d3bfe54430f8d54e0530a27f2ecbf8466576e
https://git.kernel.org/stable/c/ffaab58d217581cb75353168f8812a16e10463fc
reply other threads:[~2026-09-11 19:55 UTC|newest]
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