Linux kernel: ops.dequeue() deadlock with DSQ lock in sched_ext
CVE-2026-98865 Published on October 18, 2026
sched_ext: Don't run ops.dequeue() with a DSQ lock held
In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Don't run ops.dequeue() with a DSQ lock held
ops.dequeue() is invoked with the source user DSQ's lock still held on
the consume and move paths (scx_consume_dispatch_q(),
move_task_between_dsqs()). A BPF scheduler which locks the source user
DSQ from ops.dequeue() - e.g. by iterating it with bpf_iter_scx_dsq -
self-deadlocks.
ops.dequeue() can only call the "any" kfuncs and none of them can lock a
builtin DSQ, so the global and bypass paths can't deadlock; however,
all DSQ locks share one lockdep class, so iterating any user DSQ from
ops.dequeue() on those paths trips the recursion check.
Move the invocation after the DSQ unlock on all three paths.
SCX_TASK_IN_CUSTODY is cleared under the lock serializing the transfer
so that the callback is invoked exactly once.
Products Associated with CVE-2026-98865
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Affected Versions
Linux:- Version ebf1ccff79c43f860cbd2f9d6cfab9a462d0cb2d and below fe499ae9da46e297f578d4346c4c8e338c3118db is affected.
- Version ebf1ccff79c43f860cbd2f9d6cfab9a462d0cb2d and below cb86607ada73185f321baa7f9d94a08a3a40bbf5 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.