======================================
| [   13.753976][   T66] ==================================================================
| [ 13.754192][ T66] BUG: KASAN: slab-use-after-free in cleanup_net (net/core/net_namespace.c:462 net/core/net_namespace.c:661)
| [   13.754383][   T66] Read of size 8 at addr ffff888009d180f8 by task kworker/u16:1/66
| [   13.754560][   T66]
[   13.754810][   T66] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   13.754965][   T66] Workqueue: netns cleanup_net
[   13.755098][   T66] Call Trace:
[   13.755193][   T66]  <TASK>
[ 13.755260][ T66] dump_stack_lvl (lib/dump_stack.c:123)
[ 13.755387][ T66] print_address_description.constprop.0 (mm/kasan/report.c:379)
[ 13.755543][ T66] ? cleanup_net (net/core/net_namespace.c:462 net/core/net_namespace.c:661)
[ 13.755669][ T66] print_report (mm/kasan/report.c:490)
[ 13.755794][ T66] ? kasan_addr_to_slab (./include/linux/mm.h:1294 mm/kasan/../slab.h:211 mm/kasan/common.c:38)
[ 13.755918][ T66] kasan_report (mm/kasan/report.c:604)
[ 13.756013][ T66] ? cleanup_net (net/core/net_namespace.c:462 net/core/net_namespace.c:661)
[ 13.756139][ T66] cleanup_net (net/core/net_namespace.c:462 net/core/net_namespace.c:661)
[ 13.756264][ T66] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 13.756391][ T66] ? __pfx_cleanup_net (net/core/net_namespace.c:592)
[ 13.756518][ T66] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 47))
[ 13.756643][ T66] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 13.756768][ T66] ? process_one_work (kernel/workqueue.c:3205)
[ 13.756896][ T66] process_one_work (kernel/workqueue.c:3229)
[ 13.757019][ T66] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 13.757143][ T66] ? __pfx_process_one_work (kernel/workqueue.c:3131)
[ 13.757269][ T66] ? assign_work (kernel/workqueue.c:1200)
[ 13.757393][ T66] worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391)
[ 13.757522][ T66] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
[ 13.757678][ T66] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 13.757802][ T66] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 13.757925][ T66] kthread (kernel/kthread.c:389)
[ 13.758021][ T66] ? __pfx_kthread (kernel/kthread.c:342)
[ 13.758147][ T66] ret_from_fork (arch/x86/kernel/process.c:147)
[ 13.758270][ T66] ? __pfx_kthread (kernel/kthread.c:342)


Finger prints:
print_report:kasan_report:cleanup_net:process_one_work:worker_thread