======================================
| [   11.893260][   T66] ==================================================================
| [ 11.893571][ T66] BUG: KASAN: slab-use-after-free in cleanup_net (net/core/net_namespace.c:462 net/core/net_namespace.c:661)
| [   11.893851][   T66] Read of size 8 at addr ffff88800a9d80f8 by task kworker/u16:1/66
| [   11.894123][   T66]
[   11.894508][   T66] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   11.894746][   T66] Workqueue: netns cleanup_net
[   11.894947][   T66] Call Trace:
[   11.895091][   T66]  <TASK>
[ 11.895197][ T66] dump_stack_lvl (lib/dump_stack.c:123)
[ 11.895395][ T66] print_address_description.constprop.0 (mm/kasan/report.c:379)
[ 11.895638][ T66] ? cleanup_net (net/core/net_namespace.c:462 net/core/net_namespace.c:661)
[ 11.895831][ T66] print_report (mm/kasan/report.c:490)
[ 11.896015][ T66] ? kasan_addr_to_slab (./include/linux/mm.h:1294 mm/kasan/../slab.h:211 mm/kasan/common.c:38)
[ 11.896200][ T66] kasan_report (mm/kasan/report.c:604)
[ 11.896324][ T66] ? cleanup_net (net/core/net_namespace.c:462 net/core/net_namespace.c:661)
[ 11.896451][ T66] cleanup_net (net/core/net_namespace.c:462 net/core/net_namespace.c:661)
[ 11.896575][ T66] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 11.896721][ T66] ? __pfx_cleanup_net (net/core/net_namespace.c:592)
[ 11.896873][ T66] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 47))
[ 11.897017][ T66] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 11.897180][ T66] ? process_one_work (kernel/workqueue.c:3205)
[ 11.897348][ T66] process_one_work (kernel/workqueue.c:3229)
[ 11.897500][ T66] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 11.897675][ T66] ? __pfx_process_one_work (kernel/workqueue.c:3131)
[ 11.897824][ T66] ? assign_work (kernel/workqueue.c:1200)
[ 11.897990][ T66] worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391)
[ 11.898113][ T66] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
[ 11.898280][ T66] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 11.898405][ T66] ? __pfx_worker_thread (kernel/workqueue.c:3337)
[ 11.898528][ T66] kthread (kernel/kthread.c:389)
[ 11.898625][ T66] ? __pfx_kthread (kernel/kthread.c:342)
[ 11.898749][ T66] ret_from_fork (arch/x86/kernel/process.c:147)
[ 11.898874][ T66] ? __pfx_kthread (kernel/kthread.c:342)


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