{"id":"CVE-2026-99105","state":"PUBLISHED","title":"sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ","description":"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.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.","publishedAt":"2026-10-28T10:34:24.456Z","updatedAt":"2026-10-30T12:41:46.163Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f0e1a0643a59bf1f922fa209cec86a170b784f3f","status":"affected","lessThan":"ea47eec058fc1b6a3c3c54870d24a8bdcb3e204d","versionType":"git"},{"version":"f0e1a0643a59bf1f922fa209cec86a170b784f3f","status":"affected","lessThan":"8d891c218016b6145993e082e7f732cb69dd0e29","versionType":"git"},{"version":"f0e1a0643a59bf1f922fa209cec86a170b784f3f","status":"affected","lessThan":"396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59","versionType":"git"},{"version":"f0e1a0643a59bf1f922fa209cec86a170b784f3f","status":"affected","lessThan":"7a9df76679633cf26e0fea882a684012c6ec245a","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext/ext.c","kernel/sched/ext/internal.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.115","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.59","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext/ext.c","kernel/sched/ext/internal.h"]}],"references":["https://git.kernel.org/stable/c/ea47eec058fc1b6a3c3c54870d24a8bdcb3e204d","https://git.kernel.org/stable/c/8d891c218016b6145993e082e7f732cb69dd0e29","https://git.kernel.org/stable/c/396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59","https://git.kernel.org/stable/c/7a9df76679633cf26e0fea882a684012c6ec245a"],"weaknesses":[],"ingestedAt":"2026-10-30T13:02:04.640Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99105.json","commit":"cb14bf1b43b0c9f05f7f40eae2246263fd430780","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99105","state":"PUBLISHED","datePublished":"2026-10-28T10:34:24.456Z","dateUpdated":"2026-10-30T12:41:46.163Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.391Z"},"containers":{"cna":{"title":"sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ","descriptions":[{"lang":"en","value":"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.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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f0e1a0643a59bf1f922fa209cec86a170b784f3f","status":"affected","lessThan":"ea47eec058fc1b6a3c3c54870d24a8bdcb3e204d","versionType":"git"},{"version":"f0e1a0643a59bf1f922fa209cec86a170b784f3f","status":"affected","lessThan":"8d891c218016b6145993e082e7f732cb69dd0e29","versionType":"git"},{"version":"f0e1a0643a59bf1f922fa209cec86a170b784f3f","status":"affected","lessThan":"396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59","versionType":"git"},{"version":"f0e1a0643a59bf1f922fa209cec86a170b784f3f","status":"affected","lessThan":"7a9df76679633cf26e0fea882a684012c6ec245a","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext/ext.c","kernel/sched/ext/internal.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.115","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.59","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext/ext.c","kernel/sched/ext/internal.h"]}],"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"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:41:46.163Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.12.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.18.59"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.2.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}