ghsa-33j2-rmf2-wf3v
Vulnerability from github
Published
2025-06-18 12:30
Modified
2025-06-18 12:30
Details

In the Linux kernel, the following vulnerability has been resolved:

sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed

With cgroup v2, the cpuset's cpus_allowed mask can be empty indicating that the cpuset will just use the effective CPUs of its parent. So cpuset_can_attach() can call task_can_attach() with an empty mask. This can lead to cpumask_any_and() returns nr_cpu_ids causing the call to dl_bw_of() to crash due to percpu value access of an out of bound CPU value. For example:

[80468.182258] BUG: unable to handle page fault for address: ffffffff8b6648b0
  :
[80468.191019] RIP: 0010:dl_cpu_busy+0x30/0x2b0
  :
[80468.207946] Call Trace:
[80468.208947]  cpuset_can_attach+0xa0/0x140
[80468.209953]  cgroup_migrate_execute+0x8c/0x490
[80468.210931]  cgroup_update_dfl_csses+0x254/0x270
[80468.211898]  cgroup_subtree_control_write+0x322/0x400
[80468.212854]  kernfs_fop_write_iter+0x11c/0x1b0
[80468.213777]  new_sync_write+0x11f/0x1b0
[80468.214689]  vfs_write+0x1eb/0x280
[80468.215592]  ksys_write+0x5f/0xe0
[80468.216463]  do_syscall_64+0x5c/0x80
[80468.224287]  entry_SYSCALL_64_after_hwframe+0x44/0xae

Fix that by using effective_cpus instead. For cgroup v1, effective_cpus is the same as cpus_allowed. For v2, effective_cpus is the real cpumask to be used by tasks within the cpuset anyway.

Also update task_can_attach()'s 2nd argument name to cs_effective_cpus to reflect the change. In addition, a check is added to task_can_attach() to guard against the possibility that cpumask_any_and() may return a value >= nr_cpu_ids.

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{
  "affected": [],
  "aliases": [
    "CVE-2022-50103"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-06-18T11:15:39Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched, cpuset: Fix dl_cpu_busy() panic due to empty cs-\u003ecpus_allowed\n\nWith cgroup v2, the cpuset\u0027s cpus_allowed mask can be empty indicating\nthat the cpuset will just use the effective CPUs of its parent. So\ncpuset_can_attach() can call task_can_attach() with an empty mask.\nThis can lead to cpumask_any_and() returns nr_cpu_ids causing the call\nto dl_bw_of() to crash due to percpu value access of an out of bound\nCPU value. For example:\n\n\t[80468.182258] BUG: unable to handle page fault for address: ffffffff8b6648b0\n\t  :\n\t[80468.191019] RIP: 0010:dl_cpu_busy+0x30/0x2b0\n\t  :\n\t[80468.207946] Call Trace:\n\t[80468.208947]  cpuset_can_attach+0xa0/0x140\n\t[80468.209953]  cgroup_migrate_execute+0x8c/0x490\n\t[80468.210931]  cgroup_update_dfl_csses+0x254/0x270\n\t[80468.211898]  cgroup_subtree_control_write+0x322/0x400\n\t[80468.212854]  kernfs_fop_write_iter+0x11c/0x1b0\n\t[80468.213777]  new_sync_write+0x11f/0x1b0\n\t[80468.214689]  vfs_write+0x1eb/0x280\n\t[80468.215592]  ksys_write+0x5f/0xe0\n\t[80468.216463]  do_syscall_64+0x5c/0x80\n\t[80468.224287]  entry_SYSCALL_64_after_hwframe+0x44/0xae\n\nFix that by using effective_cpus instead. For cgroup v1, effective_cpus\nis the same as cpus_allowed. For v2, effective_cpus is the real cpumask\nto be used by tasks within the cpuset anyway.\n\nAlso update task_can_attach()\u0027s 2nd argument name to cs_effective_cpus to\nreflect the change. In addition, a check is added to task_can_attach()\nto guard against the possibility that cpumask_any_and() may return a\nvalue \u003e= nr_cpu_ids.",
  "id": "GHSA-33j2-rmf2-wf3v",
  "modified": "2025-06-18T12:30:48Z",
  "published": "2025-06-18T12:30:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-50103"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/147f66d22f58712dce7ccdd6a1f6cb3ee8042df4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/336626564b58071b8980a4e6a31a8f5d92705d9b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/357f3f0e522a6ce1ce4a571cb780d9861d53bec7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b6e8d40d43ae4dec00c8fea2593eeea3114b8f44"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f56607b44c9896e51678a7e8cdd3a5479f4b4548"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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