title: tipc: wait and exit until all work queues are done
description: In the Linux kernel, the following vulnerability has been resolved:
tipc: wait and exit until all work queues are done
On some host, a crash could be triggered simply by repeating these
commands several times:
# modprobe tipc
# tipc bearer enable media udp name UDP1 localip 127.0.0.1
# rmmod tipc
[] BUG: unable to handle kernel paging request at ffffffffc096bb00
[] Workqueue: events 0xffffffffc096bb00
[] Call Trace:
[]  ? process_one_work+0x1a7/0x360
[]  ? worker_thread+0x30/0x390
[]  ? create_worker+0x1a0/0x1a0
[]  ? kthread+0x116/0x130
[]  ? kthread_flush_work_fn+0x10/0x10
[]  ? ret_from_fork+0x35/0x40
When removing the TIPC module, the UDP tunnel sock will be delayed to
release in a work queue as sock_release() can't be done in rtnl_lock().
If the work queue is schedule to run after the TIPC module is removed,
kernel will crash as the work queue function cleanup_beareri() code no
longer exists when trying to invoke it.
To fix it, this patch introduce a member wq_count in tipc_net to track
the numbers of work queues in schedule, and  wait and exit until all
work queues are done in tipc_exit_net().
affected:
{
product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: d0f91938bede, lessThan: d1f76dfadaf8, status: affected, versionType: git
version: d0f91938bede, lessThan: 5195ec5e365a, status: affected, versionType: git
version: d0f91938bede, lessThan: b9f5b7ad4ac3, status: affected, versionType: git
version: d0f91938bede, lessThan: 04c26faa51d1, status: affected, versionType: git
}
{
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 4.1, status: affected
version: 0, lessThan: 4.1, status: unaffected, versionType: custom
version: 5.4.124, lessThanOrEqual: 5.4.*, status: unaffected, versionType: custom
version: 5.10.42, lessThanOrEqual: 5.10.*, status: unaffected, versionType: custom
version: 5.12.9, lessThanOrEqual: 5.12.*, status: unaffected, versionType: custom
version: 5.13, lessThanOrEqual: *, status: unaffected, versionType: original_commit_for_fix
}
