fkie_cve-2025-68319
Vulnerability from fkie_nvd
Published
2025-12-16 16:16
Modified
2025-12-18 15:08
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: netconsole: Acquire su_mutex before navigating configs hierarchy There is a race between operations that iterate over the userdata cg_children list and concurrent add/remove of userdata items through configfs. The update_userdata() function iterates over the nt->userdata_group.cg_children list, and count_extradata_entries() also iterates over this same list to count nodes. Quoting from Documentation/filesystems/configfs.rst: > A subsystem can navigate the cg_children list and the ci_parent pointer > to see the tree created by the subsystem. This can race with configfs' > management of the hierarchy, so configfs uses the subsystem mutex to > protect modifications. Whenever a subsystem wants to navigate the > hierarchy, it must do so under the protection of the subsystem > mutex. Without proper locking, if a userdata item is added or removed concurrently while these functions are iterating, the list can be accessed in an inconsistent state. For example, the list_for_each() loop can reach a node that is being removed from the list by list_del_init() which sets the nodes' .next pointer to point to itself, so the loop will never end (or reach the WARN_ON_ONCE in update_userdata() ). Fix this by holding the configfs subsystem mutex (su_mutex) during all operations that iterate over cg_children. This includes: - userdatum_value_store() which calls update_userdata() to iterate over cg_children - All sysdata_*_enabled_store() functions which call count_extradata_entries() to iterate over cg_children The su_mutex must be acquired before dynamic_netconsole_mutex to avoid potential lock ordering issues, as configfs operations may already hold su_mutex when calling into our code.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d7d2fcf7ae31471b4e08b7e448b8fd0ec2e06a1b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ff70aa7e8cf05745fdba7258952a8bedf33ea336
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetconsole: Acquire su_mutex before navigating configs hierarchy\n\nThere is a race between operations that iterate over the userdata\ncg_children list and concurrent add/remove of userdata items through\nconfigfs. The update_userdata() function iterates over the\nnt-\u003euserdata_group.cg_children list, and count_extradata_entries() also\niterates over this same list to count nodes.\n\nQuoting from Documentation/filesystems/configfs.rst:\n\u003e A subsystem can navigate the cg_children list and the ci_parent pointer\n\u003e to see the tree created by the subsystem.  This can race with configfs\u0027\n\u003e management of the hierarchy, so configfs uses the subsystem mutex to\n\u003e protect modifications.  Whenever a subsystem wants to navigate the\n\u003e hierarchy, it must do so under the protection of the subsystem\n\u003e mutex.\n\nWithout proper locking, if a userdata item is added or removed\nconcurrently while these functions are iterating, the list can be\naccessed in an inconsistent state. For example, the list_for_each() loop\ncan reach a node that is being removed from the list by list_del_init()\nwhich sets the nodes\u0027 .next pointer to point to itself, so the loop will\nnever end (or reach the WARN_ON_ONCE in update_userdata() ).\n\nFix this by holding the configfs subsystem mutex (su_mutex) during all\noperations that iterate over cg_children.\nThis includes:\n- userdatum_value_store() which calls update_userdata() to iterate over\n  cg_children\n- All sysdata_*_enabled_store() functions which call\n  count_extradata_entries() to iterate over cg_children\n\nThe su_mutex must be acquired before dynamic_netconsole_mutex to avoid\npotential lock ordering issues, as configfs operations may already hold\nsu_mutex when calling into our code."
    }
  ],
  "id": "CVE-2025-68319",
  "lastModified": "2025-12-18T15:08:06.237",
  "metrics": {},
  "published": "2025-12-16T16:16:11.483",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d7d2fcf7ae31471b4e08b7e448b8fd0ec2e06a1b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ff70aa7e8cf05745fdba7258952a8bedf33ea336"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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