Affected: Alpaquita:25: linux-lts, Alpaquita:stream: linux-lts

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…

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…

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 103 more

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_*_en…

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um nicht näher spezifizierte Angriffe durchzuführen, die möglicherweise zu einer Denial-of-Service- Bedingung führen oder eine Speicherbeschädigung verursachen können.