CVE-2026-98542 (GCVE-0-2026-98542)
Vulnerability from cvelistv5
Published
2026-10-18 15:18
Modified
2026-10-19 09:21
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict When a remote partition is created underneath an existing local partition via a non-partition (PRS_MEMBER) intermediate cgroup, update_prstate() sees parent->partition_root_state == PRS_MEMBER and calls remote_partition_enable(). Commit 86888c7bd117 ("cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs") replaced the cpumask_intersects(tmp->new_cpus, subpartitions_cpus) error check in remote_partition_enable() with WARN_ON_ONCE(). As a result, remote_partition_enable() emits a warning and proceeds to enable the remote partition on CPUs that are already owned by the ancestor local partition in subpartitions_cpus. This can be reproduced on Linux 7.3.0-rc3 with: mkdir -p /tmp/cg1 mount -t cgroup2 none /tmp/cg1 echo "+cpuset" > /tmp/cg1/cgroup.subtree_control mkdir /tmp/cg1/A echo 1 > /tmp/cg1/A/cpuset.cpus echo 1 > /tmp/cg1/A/cpuset.cpus.exclusive echo root > /tmp/cg1/A/cpuset.cpus.partition echo "+cpuset" > /tmp/cg1/A/cgroup.subtree_control mkdir /tmp/cg1/A/B echo 1 > /tmp/cg1/A/B/cpuset.cpus echo 1 > /tmp/cg1/A/B/cpuset.cpus.exclusive echo "+cpuset" > /tmp/cg1/A/B/cgroup.subtree_control mkdir /tmp/cg1/A/B/D echo 1 > /tmp/cg1/A/B/D/cpuset.cpus echo 1 > /tmp/cg1/A/B/D/cpuset.cpus.exclusive echo root > /tmp/cg1/A/B/D/cpuset.cpus.partition which triggers: WARNING: kernel/cgroup/cpuset.c:1594 at remote_partition_enable+0x1c1/0x300 and leaves both /tmp/cg1/A and /tmp/cg1/A/B/D as active root partitions claiming exclusive CPU 1. Fix this by returning PERR_NOCPUS when tmp->new_cpus intersects subpartitions_cpus in remote_partition_enable(), matching the error code used by remote_cpus_update() for the same subpartitions_cpus conflict, and add a regression test case to tools/testing/selftests/cgroup/test_cpuset_prs.sh. Tested in QEMU on Linux 7.3.0-rc3 using the reproducer above and tools/testing/selftests/cgroup/test_cpuset_prs.sh.
References
Impacted products
Vendor Product Version
Linux Linux Version: 86888c7bd117c29eab169c37e5f6bbbf583da983
Version: 86888c7bd117c29eab169c37e5f6bbbf583da983
Version: 86888c7bd117c29eab169c37e5f6bbbf583da983
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/cgroup/cpuset.c",
            "tools/testing/selftests/cgroup/test_cpuset_prs.sh"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "241e67b60308cdce25bba66616a109759edd1d40",
              "status": "affected",
              "version": "86888c7bd117c29eab169c37e5f6bbbf583da983",
              "versionType": "git"
            },
            {
              "lessThan": "0751ab665cb3dcdac224b002565f2e28461740d5",
              "status": "affected",
              "version": "86888c7bd117c29eab169c37e5f6bbbf583da983",
              "versionType": "git"
            },
            {
              "lessThan": "31c88350b7dd1522792f726f79607f31bb55c50f",
              "status": "affected",
              "version": "86888c7bd117c29eab169c37e5f6bbbf583da983",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/cgroup/cpuset.c",
            "tools/testing/selftests/cgroup/test_cpuset_prs.sh"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.55",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.9",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict\n\nWhen a remote partition is created underneath an existing local partition\nvia a non-partition (PRS_MEMBER) intermediate cgroup, update_prstate() sees\nparent-\u003epartition_root_state == PRS_MEMBER and calls\nremote_partition_enable().\n\nCommit 86888c7bd117 (\"cgroup/cpuset: Add warnings to catch inconsistency\nin exclusive CPUs\") replaced the cpumask_intersects(tmp-\u003enew_cpus,\nsubpartitions_cpus) error check in remote_partition_enable() with\nWARN_ON_ONCE(). As a result, remote_partition_enable() emits a warning\nand proceeds to enable the remote partition on CPUs that are already\nowned by the ancestor local partition in subpartitions_cpus.\n\nThis can be reproduced on Linux 7.3.0-rc3 with:\n\n  mkdir -p /tmp/cg1\n  mount -t cgroup2 none /tmp/cg1\n  echo \"+cpuset\" \u003e /tmp/cg1/cgroup.subtree_control\n\n  mkdir /tmp/cg1/A\n  echo 1 \u003e /tmp/cg1/A/cpuset.cpus\n  echo 1 \u003e /tmp/cg1/A/cpuset.cpus.exclusive\n  echo root \u003e /tmp/cg1/A/cpuset.cpus.partition\n  echo \"+cpuset\" \u003e /tmp/cg1/A/cgroup.subtree_control\n\n  mkdir /tmp/cg1/A/B\n  echo 1 \u003e /tmp/cg1/A/B/cpuset.cpus\n  echo 1 \u003e /tmp/cg1/A/B/cpuset.cpus.exclusive\n  echo \"+cpuset\" \u003e /tmp/cg1/A/B/cgroup.subtree_control\n\n  mkdir /tmp/cg1/A/B/D\n  echo 1 \u003e /tmp/cg1/A/B/D/cpuset.cpus\n  echo 1 \u003e /tmp/cg1/A/B/D/cpuset.cpus.exclusive\n  echo root \u003e /tmp/cg1/A/B/D/cpuset.cpus.partition\n\nwhich triggers:\n\n  WARNING: kernel/cgroup/cpuset.c:1594 at remote_partition_enable+0x1c1/0x300\n\nand leaves both /tmp/cg1/A and /tmp/cg1/A/B/D as active root partitions\nclaiming exclusive CPU 1.\n\nFix this by returning PERR_NOCPUS when tmp-\u003enew_cpus intersects\nsubpartitions_cpus in remote_partition_enable(), matching the error code\nused by remote_cpus_update() for the same subpartitions_cpus conflict, and\nadd a regression test case to\ntools/testing/selftests/cgroup/test_cpuset_prs.sh.\n\nTested in QEMU on Linux 7.3.0-rc3 using the reproducer above and\ntools/testing/selftests/cgroup/test_cpuset_prs.sh."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:21:25.599Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/241e67b60308cdce25bba66616a109759edd1d40"
        },
        {
          "url": "https://git.kernel.org/stable/c/0751ab665cb3dcdac224b002565f2e28461740d5"
        },
        {
          "url": "https://git.kernel.org/stable/c/31c88350b7dd1522792f726f79607f31bb55c50f"
        }
      ],
      "title": "cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98542",
    "datePublished": "2026-10-18T15:18:10.035Z",
    "dateReserved": "2026-09-25T10:25:14.356Z",
    "dateUpdated": "2026-10-19T09:21:25.599Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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