CVE-2026-98542 (GCVE-0-2026-98542)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:18 – Updated: 2026-10-19 09:21
VLAI
Title
cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict
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.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6637 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 86888c7bd117c29eab169c37e5f6bbbf583da983 , < 241e67b60308cdce25bba66616a109759edd1d40 (git)
Affected: 86888c7bd117c29eab169c37e5f6bbbf583da983 , < 0751ab665cb3dcdac224b002565f2e28461740d5 (git)
Affected: 86888c7bd117c29eab169c37e5f6bbbf583da983 , < 31c88350b7dd1522792f726f79607f31bb55c50f (git)
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Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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              "operator": "OR"
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      "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."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:21:25.599Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/31c88350b7dd1522792f726f79607f31bb55c50f"
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      "title": "cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict",
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    "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"
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      "id": "msrc_CVE-2026-98542",
      "initial_release_date": "2026-10-20T22:23:34.000Z",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98542.json",
      "version": "2"
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          {
            "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."
          }
        ],
        "id": "CVE-2026-98542",
        "lastModified": "2026-10-19T10:19:10.107",
        "metrics": {},
        "published": "2026-10-18T16:17:06.090",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/0751ab665cb3dcdac224b002565f2e28461740d5"
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        "vulnStatus": "Received"
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      "current_release_date": "2026-10-30T08:20:26+00:00",
      "cve": "CVE-2026-98542",
      "id": "CVE-2026-98542",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_affected": "186",
      "product_status:known_not_affected": "93",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98542.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-11-04T17:57:20Z",
      "cve": "CVE-2026-98542",
      "id": "CVE-2026-98542",
      "initial_release_date": "2026-10-21T16:54:54Z",
      "product_status:known_not_affected": "348",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-98542",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-98542.json",
      "version": "3"
    }
  }
}



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