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.
Metrics
Affected Vendors & Products
References
History
Tue, 16 Dec 2025 15:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | netconsole: Acquire su_mutex before navigating configs hierarchy | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-12-16T15:39:48.903Z
Reserved: 2025-12-16T14:48:05.295Z
Link: CVE-2025-68319
No data.
Status : Received
Published: 2025-12-16T16:16:11.483
Modified: 2025-12-16T16:16:11.483
Link: CVE-2025-68319
No data.
OpenCVE Enrichment
No data.