{"schema":"threatline.record/2","record":{"id":"CVE-2026-98542","aliases":[],"summary":"cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict","details":"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->partition_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->new_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\" > /tmp/cg1/cgroup.subtree_control\n\n  mkdir /tmp/cg1/A\n  echo 1 > /tmp/cg1/A/cpuset.cpus\n  echo 1 > /tmp/cg1/A/cpuset.cpus.exclusive\n  echo root > /tmp/cg1/A/cpuset.cpus.partition\n  echo \"+cpuset\" > /tmp/cg1/A/cgroup.subtree_control\n\n  mkdir /tmp/cg1/A/B\n  echo 1 > /tmp/cg1/A/B/cpuset.cpus\n  echo 1 > /tmp/cg1/A/B/cpuset.cpus.exclusive\n  echo \"+cpuset\" > /tmp/cg1/A/B/cgroup.subtree_control\n\n  mkdir /tmp/cg1/A/B/D\n  echo 1 > /tmp/cg1/A/B/D/cpuset.cpus\n  echo 1 > /tmp/cg1/A/B/D/cpuset.cpus.exclusive\n  echo root > /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->new_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.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98542","source_modified_at":"2026-10-19T09:21:25.599Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"86888c7bd117c29eab169c37e5f6bbbf583da983","lessThan":"241e67b60308cdce25bba66616a109759edd1d40","status":"affected","versionType":"git"},{"version":"86888c7bd117c29eab169c37e5f6bbbf583da983","lessThan":"0751ab665cb3dcdac224b002565f2e28461740d5","status":"affected","versionType":"git"},{"version":"86888c7bd117c29eab169c37e5f6bbbf583da983","lessThan":"31c88350b7dd1522792f726f79607f31bb55c50f","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98542","source_modified_at":"2026-10-19T09:21:25.599Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"6.16","status":"affected"},{"version":"0","lessThan":"6.16","status":"unaffected","versionType":"semver"},{"version":"6.18.55","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.9","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98542","source_modified_at":"2026-10-19T09:21:25.599Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"241e67b60308cdce25bba66616a109759edd1d40","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98542","source_modified_at":"2026-10-19T09:21:25.599Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"0751ab665cb3dcdac224b002565f2e28461740d5","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98542","source_modified_at":"2026-10-19T09:21:25.599Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"31c88350b7dd1522792f726f79607f31bb55c50f","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.00198,"percentile":0.09056,"score_date":"2026-10-23"},"published_at":"2026-10-18T15:18:10.035Z","modified_at":"2026-10-19T09:21:25.599Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98542","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T09:21:25.599Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98542","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/241e67b60308cdce25bba66616a109759edd1d40"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/0751ab665cb3dcdac224b002565f2e28461740d5"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/31c88350b7dd1522792f726f79607f31bb55c50f"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T09:21:25.599Z","content_hash":"ff12d8682bbe831acced96bcf901ffdd4ecceda89ee4dbe0a543248903f841c6"}}