cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode()

{
  "id": "f58739398a51864a86ef172833016f0e44644e333a59a281857be26cf9d83a2f",
  "url": "https://osv.dev/vulnerability/CVE-2026-98972",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode() After seeing the patch [1] to guard is_in_v2_mode() with RCU, it makes me realize that is_in_v2_mode() may be called in a context where a new cgroup filesystem is being rebound with stale cpuset_cgrp_subsys.root pointer. Avoid this potential UaF situation by adding a new cpuset_v2_mode flag which is set when the cpuset_v2_mode mount option is used. This flag is written into only when cpuset_bind() is being called with a stable cpuset_cgrp_subsys.root value. The is_in_v2_mode() helper is modified to read the new cpuset_v2_mode flag instead of accessing cpuset_cgrp_subsys.root directly. [1] https://lore.kernel.org/lkml/20260929084124.626693-2-arighi@nvidia.com",
    "evidence": "osv:CVE-2026-98972",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.2.11",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98972",
      "aliases": [
        "CVE-2026-98972"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "b8d1b8ee93df8ffbabbeadd65d39853cfad6d698"
                },
                {
                  "fixed": "988bf67a13890a37a33201f95947095ca9bec856"
                },
                {
                  "fixed": "e06b678e3b4e12fdaa0b51a7a5a54abc5dbd6469"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98972.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "4.14.0"
                },
                {
                  "fixed": "7.2.11"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98972.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:33.017379557Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/988bf67a13890a37a33201f95947095ca9bec856",
        "https://git.kernel.org/stable/c/e06b678e3b4e12fdaa0b51a7a5a54abc5dbd6469",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98972.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98972",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98972.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98972",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 500189,
  "published_at": "2026-10-23T12:19:45.458+00:00"
}