{"cve":"CVE-2026-31733","nvd":{"published":"2026-05-01T15:16:35.913","modified":"2026-06-17T10:34:19.890","status":"Analyzed","description":"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->scx.ddsp_dsq_id can be left set (non-SCX_DSQ_INVALID) triggering a\nspurious warning in mark_direct_dispatch() when the next wakeup's\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's\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't 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().","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/5e7b2cc8fae9ec2a5bc53311191d2faaff75a4b5","https://git.kernel.org/stable/c/7e0ffb72de8aa3b25989c2d980e81b829c577010","https://git.kernel.org/stable/c/7ea601daa0153e19cd1c6e6b300348c70c05fe77","https://git.kernel.org/stable/c/ca685511f7afd42cdcbb0feea42e5d332d384251"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:33:09.003606135+00:00"},"epss":{"cve":"CVE-2026-31733","score":0.0013,"percentile":0.02592,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}