Vulnerability-Lookup

FKIE_CVE-2026-31733

Vulnerability from fkie_nvd - Published: 2026-05-01 15:16 - Updated: 2026-05-07 16:44

Severity ?

5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix stale direct dispatch state in ddsp_dsq_id @p->scx.ddsp_dsq_id can be left set (non-SCX_DSQ_INVALID) triggering a spurious warning in mark_direct_dispatch() when the next wakeup's ops.select_cpu() calls scx_bpf_dsq_insert(), such as: WARNING: kernel/sched/ext.c:1273 at scx_dsq_insert_commit+0xcd/0x140 The root cause is that ddsp_dsq_id was only cleared in dispatch_enqueue(), which is not reached in all paths that consume or cancel a direct dispatch verdict. Fix it by clearing it at the right places: - direct_dispatch(): cache the direct dispatch state in local variables and clear it before dispatch_enqueue() on the synchronous path. For the deferred path, the direct dispatch state must remain set until process_ddsp_deferred_locals() consumes them. - process_ddsp_deferred_locals(): cache the dispatch state in local variables and clear it before calling dispatch_to_local_dsq(), which may migrate the task to another rq. - do_enqueue_task(): clear the dispatch state on the enqueue path (local/global/bypass fallbacks), where the direct dispatch verdict is ignored. - dequeue_task_scx(): clear the dispatch state after dispatch_dequeue() to handle both the deferred dispatch cancellation and the holding_cpu race, covering all cases where a pending direct dispatch is cancelled. - scx_disable_task(): clear the direct dispatch state when transitioning a task out of the current scheduler. Waking tasks may have had the direct dispatch state set by the outgoing scheduler's ops.select_cpu() and then been queued on a wake_list via ttwu_queue_wakelist(), when SCX_OPS_ALLOW_QUEUED_WAKEUP is set. Such tasks are not on the runqueue and are not iterated by scx_bypass(), so their direct dispatch state won't be cleared. Without this clear, any subsequent SCX scheduler that tries to direct dispatch the task will trigger the WARN_ON_ONCE() in mark_direct_dispatch().

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/5e7b2cc8fae9ec2a5bc53311191d2faaff75a4b5	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7e0ffb72de8aa3b25989c2d980e81b829c577010	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7ea601daa0153e19cd1c6e6b300348c70c05fe77	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ca685511f7afd42cdcbb0feea42e5d332d384251	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0

JSON

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix stale direct dispatch state in ddsp_dsq_id\n\n@p-\u003escx.ddsp_dsq_id can be left set (non-SCX_DSQ_INVALID) triggering a\nspurious warning in mark_direct_dispatch() when the next wakeup\u0027s\nops.select_cpu() calls scx_bpf_dsq_insert(), such as:\n\n WARNING: kernel/sched/ext.c:1273 at scx_dsq_insert_commit+0xcd/0x140\n\nThe root cause is that ddsp_dsq_id was only cleared in dispatch_enqueue(),\nwhich is not reached in all paths that consume or cancel a direct dispatch\nverdict.\n\nFix it by clearing it at the right places:\n\n - direct_dispatch(): cache the direct dispatch state in local variables\n   and clear it before dispatch_enqueue() on the synchronous path. For\n   the deferred path, the direct dispatch state must remain set until\n   process_ddsp_deferred_locals() consumes them.\n\n - process_ddsp_deferred_locals(): cache the dispatch state in local\n   variables and clear it before calling dispatch_to_local_dsq(), which\n   may migrate the task to another rq.\n\n - do_enqueue_task(): clear the dispatch state on the enqueue path\n   (local/global/bypass fallbacks), where the direct dispatch verdict is\n   ignored.\n\n - dequeue_task_scx(): clear the dispatch state after dispatch_dequeue()\n   to handle both the deferred dispatch cancellation and the holding_cpu\n   race, covering all cases where a pending direct dispatch is\n   cancelled.\n\n - scx_disable_task(): clear the direct dispatch state when\n   transitioning a task out of the current scheduler. Waking tasks may\n   have had the direct dispatch state set by the outgoing scheduler\u0027s\n   ops.select_cpu() and then been queued on a wake_list via\n   ttwu_queue_wakelist(), when SCX_OPS_ALLOW_QUEUED_WAKEUP is set. Such\n   tasks are not on the runqueue and are not iterated by scx_bypass(),\n   so their direct dispatch state won\u0027t be cleared. Without this clear,\n   any subsequent SCX scheduler that tries to direct dispatch the task\n   will trigger the WARN_ON_ONCE() in mark_direct_dispatch()."
    }
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  "lastModified": "2026-05-07T16:44:45.520",
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}

CVE-2026-31733 (GCVE-0-2026-31733)

Vulnerability from cvelistv5 – Published: 2026-05-01 14:14 – Updated: 2026-05-11 22:14

Title

sched_ext: Fix stale direct dispatch state in ddsp_dsq_id

Summary

Severity ?

No CVSS data available.

Assigner

Linux

References

4 references

URL	Tags
https://git.kernel.org/stable/c/ca685511f7afd42cd…
https://git.kernel.org/stable/c/5e7b2cc8fae9ec2a5…
https://git.kernel.org/stable/c/7ea601daa0153e19c…
https://git.kernel.org/stable/c/7e0ffb72de8aa3b25…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 5b26f7b920f76b2b9cc398c252a9e35e44bf5bb9 , < ca685511f7afd42cdcbb0feea42e5d332d384251 (git) Affected: 5b26f7b920f76b2b9cc398c252a9e35e44bf5bb9 , < 5e7b2cc8fae9ec2a5bc53311191d2faaff75a4b5 (git) Affected: 5b26f7b920f76b2b9cc398c252a9e35e44bf5bb9 , < 7ea601daa0153e19cd1c6e6b300348c70c05fe77 (git) Affected: 5b26f7b920f76b2b9cc398c252a9e35e44bf5bb9 , < 7e0ffb72de8aa3b25989c2d980e81b829c577010 (git)
Linux	Linux	Affected: 6.12 Unaffected: 0 , < 6.12 (semver) Unaffected: 6.12.82 , ≤ 6.12.* (semver) Unaffected: 6.18.22 , ≤ 6.18.* (semver) Unaffected: 6.19.12 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

FKIE_CVE-2026-31733

CVE-2026-31733 (GCVE-0-2026-31733)

Tags

Sightings

Nomenclature