{"id":"CVE-2026-99105","title":"sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ\n\nWith SCX_OPS_ENQ_LAST, the last runnable task on a CPU is passed to\nops.e…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= f0e1a0643a59bf1f922fa209cec86a170b784f3f < ea47eec058fc1b6a3c3c54870d24a8bdcb3e204d","Linux >= f0e1a0643a59bf1f922fa209cec86a170b784f3f < 8d891c218016b6145993e082e7f732cb69dd0e29","Linux >= f0e1a0643a59bf1f922fa209cec86a170b784f3f < 396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59","Linux >= f0e1a0643a59bf1f922fa209cec86a170b784f3f < 7a9df76679633cf26e0fea882a684012c6ec245a","Linux 6.12"],"published":"2026-10-28","updated":"2026-10-30","sourceUpdated":"2026-10-30T12:41:46.163Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99105","references":[{"url":"https://git.kernel.org/stable/c/ea47eec058fc1b6a3c3c54870d24a8bdcb3e204d"},{"url":"https://git.kernel.org/stable/c/8d891c218016b6145993e082e7f732cb69dd0e29"},{"url":"https://git.kernel.org/stable/c/396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59"},{"url":"https://git.kernel.org/stable/c/7a9df76679633cf26e0fea882a684012c6ec245a"}],"tags":["cve.org"],"epss":0.00168,"epssPercentile":0.0622,"ingestedAt":"2026-10-28T11:09:40.456Z","slug":"CVE-2026-99105","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ\n\nWith SCX_OPS_ENQ_LAST, the last runnable task on a CPU is passed to\nops.enqueue() instead of being kept running. Exiting tasks without\nSCX_OPS_ENQ_EXITING, migration disabled tasks without\nSCX_OPS_ENQ_MIGRATION_DISABLED and tasks on an offline rq skip ops.enqueue()\nand go straight to the local DSQ. This happens in put_prev_task_scx() after\nthe pick has settled on idle, so nothing reschedules the CPU, which idles\nwith the task queued until an unrelated wakeup lands on it or the watchdog\nfires.\n\nscx_mitosis, which sets SCX_OPS_ENQ_LAST without SCX_OPS_ENQ_EXITING, hit\nthis during mass cgroup teardown: exiting tasks stuck in exit_mmap() for\nover 40 seconds.\n\nA task put on the local DSQ runs, as anywhere else. If the SCX_ENQ_LAST\nenqueue left the task on this CPU's local DSQ, set need_resched on the task\nbeing switched in, as proxy_resched_idle() does. resched_curr() would flag\nthe task being put instead, and __schedule() clears that right after the\npick.\n\n## Affected\n\n- `Linux >= f0e1a0643a59bf1f922fa209cec86a170b784f3f < ea47eec058fc1b6a3c3c54870d24a8bdcb3e204d`\n- `Linux >= f0e1a0643a59bf1f922fa209cec86a170b784f3f < 8d891c218016b6145993e082e7f732cb69dd0e29`\n- `Linux >= f0e1a0643a59bf1f922fa209cec86a170b784f3f < 396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59`\n- `Linux >= f0e1a0643a59bf1f922fa209cec86a170b784f3f < 7a9df76679633cf26e0fea882a684012c6ec245a`\n- `Linux 6.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}