{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2026-46223",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-46223",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-05-28T09:40:40.791Z",
    "updatedAt": "2026-06-14T18:03:52.610Z",
    "importedAt": "2026-10-24T01:58:14.884Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "cgroup: Defer css percpu_ref kill on rmdir until cgroup is depopulated",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup: Defer css percpu_ref kill on rmdir until cgroup is depopulated\n\nA chain of commits going back to v7.0 reworked rmdir to satisfy the\ncontroller invariant that a subsystem's ->css_offline() must not run while\ntasks are still doing kernel-side work in the cgroup.\n\n[1] d245698d727a (\"cgroup: Defer task cgroup unlink until after the task is done switching out\")\n[2] a72f73c4dd9b (\"cgroup: Don't expose dead tasks in cgroup\")\n[3] 1b164b876c36 (\"cgroup: Wait for dying tasks to leave on rmdir\")\n[4] 4c56a8ac6869 (\"cgroup: Fix cgroup_drain_dying() testing the wrong condition\")\n[5] 13e786b64bd3 (\"cgroup: Increment nr_dying_subsys_* from rmdir context\")\n\n[1] moved task cset unlink from do_exit() to finish_task_switch() so a\ntask's cset link drops only after the task has fully stopped scheduling.\nThat made tasks past exit_signals() linger on cset->tasks until their final\ncontext switch, which led to a series of problems as what userspace expected\nto see after rmdir diverged from what the kernel needs to wait for. [2]-[5]\ntried to bridge that divergence: [2] filtered the exiting tasks from\ncgroup.procs; [3] had rmdir(2) sleep in TASK_UNINTERRUPTIBLE for them; [4]\nfixed the wait's condition; [5] made nr_dying_subsys_* visible\nsynchronously.\n\nThe cgroup_drain_dying() wait in [3] turned out to be a dead end. When the\nrmdir caller is also the reaper of a zombie that pins a pidns teardown (e.g.\nhost PID 1 systemd reaping orphan pids that were re-parented to it during\nthe same teardown), rmdir blocks in TASK_UNINTERRUPTIBLE waiting for those\npids to free, the pids can't free because PID 1 is the reaper and it's stuck\nin rmdir, and the system A-A deadlocks. No internal lock ordering breaks\nthis; the wait itself is the bug.\n\nThe css killing side that drove the original reorder, however, can be made\ncleanly asynchronous: ->css_offline() is already async, run from\ncss_killed_work_fn() driven by percpu_ref_kill_and_confirm(). The fix is to\nmake that chain start only after all tasks have left the cgroup. rmdir's\nuser-visible side then returns as soon as cgroup.procs and friends are\nempty, while ->css_offline() still runs only after the cgroup is fully\ndrained.\n\nVerified by the original reproducer (pidns teardown + zombie reaper, runs\nunder vng) which hangs vanilla and succeeds here, and by per-commit\ndeterministic repros for [2], [3], [4], [5] with a boot parameter that\nwidens the post-exit_signals() window so each state is reliably reachable.\nSome stress tests on top of that.\n\ncgroup_apply_control_disable() has the same shape of pre-existing race:\nwhen a controller is disabled via subtree_control, kill_css() ran\nsynchronously while tasks past exit_signals() could still be linked to\nthe cgroup's csets, and ->css_offline() could fire before they drained.\nThis patch preserves the existing synchronous behavior at that call site\n(kill_css_sync() + kill_css_finish() back-to-back) and a follow-up patch\nwill defer kill_css_finish() there using a per-css trigger.\n\nThis seems like the right approach and I don't see problems with it. The\nchanges are somewhat invasive but not excessively so, so backporting to\n-stable should be okay. If something does turn out to be wrong, the fallback\nis to revert the entire chain ([1]-[5]) and rework in the development branch\ninstead.\n\nv2: Pin cgrp across the deferred destroy work with explicit\n    cgroup_get()/cgroup_put() around queue_work() and the work_fn. v1\n    wasn't actually broken (ordered cgroup_offline_wq + queue_work order\n    in cgroup_task_dead() saved it) but the explicit ref removes the\n    dependency on those non-obvious invariants. Also note the\n    pre-existing cgroup_apply_control_disable() race in the description;\n    a follow-up will defer kill_css_finish() there.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "1b164b876c36c3eb5561dd9b37702b04401b0166",
              "status": "affected",
              "versionType": "git",
              "lessThan": "33fa2e6b1507a0a377a151a8826438bedad1d0b0"
            },
            {
              "version": "1b164b876c36c3eb5561dd9b37702b04401b0166",
              "status": "affected",
              "versionType": "git",
              "lessThan": "93618edf753838a727dbff63c7c291dee22d656b"
            },
            {
              "version": "78c72bce4a87819126211c0d24e18350010604fb",
              "status": "affected",
              "versionType": "git"
            },
            {
              "version": "6.19.12",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "6.20"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "7.0",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "7.0"
            },
            {
              "version": "7.0.9",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "7.0.*"
            },
            {
              "version": "7.1",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}