Linux Kernel: sched_ext Reenqueue Race Fix
CVE-2026-98864 Published on October 18, 2026
sched_ext: Wait for SCX_OPSS_DISPATCHING before reenqueueing a task
In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Wait for SCX_OPSS_DISPATCHING before reenqueueing a task
ebf1ccff79c4 ("sched_ext: Fix ops.dequeue() semantics") moved the final
ops_state store in scx_dispatch_enqueue() after the DSQ unlock so that the
custody update and ops.dequeue() precede it. A task can thus be found on a
DSQ while still SCX_OPSS_DISPATCHING.
The dequeue and core-sched pick paths wait for the state to clear in
ops_dequeue() but the reenqueue paths don't. A reenqueue in that window runs
ops.enqueue() and sets SCX_OPSS_QUEUED before the dispatch has completed.
The dispatcher's final store then overwrites it with SCX_OPSS_NONE and
finish_dispatch() drops every later dispatch of the task.
Wait for SCX_OPSS_DISPATCHING to clear before dequeueing a task for
reenqueue, the same way ops_dequeue() does.
Products Associated with CVE-2026-98864
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Affected Versions
Linux:- Version ebf1ccff79c43f860cbd2f9d6cfab9a462d0cb2d and below 43457bf6550044c40bd6d3fcdf9ea66f5a55d139 is affected.
- Version ebf1ccff79c43f860cbd2f9d6cfab9a462d0cb2d and below 7de9a6fb44eae4f05e68c805d58b9c618815adfa is affected.
- Version 7.1 is affected.
- Before 7.1 is unaffected.
- Version 7.2.10, <= 7.2.* is unaffected.
- Version 7.3-rc5, <= * is unaffected.