======================================
| xx__-> [   21.806077][   T69] ==================================================================
| [   21.806395][   T69] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   21.806709][   T69] Read of size 1 at addr ffff888005b716c4 by task kworker/u16:1/69
| [   21.807078][   T69]
[   21.807186][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   21.807190][   T69] Workqueue: netns cleanup_net
[   21.807200][   T69] Call Trace:
[   21.807203][   T69]  <TASK>
[   21.807207][   T69]  dump_stack_lvl (lib/dump_stack.c:123)
[   21.807219][   T69]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   21.807231][   T69]  ? kobject_put (lib/kobject.c:733)
[   21.807238][   T69]  print_report (mm/kasan/report.c:483)
[   21.807244][   T69]  ? kobject_put (lib/kobject.c:733)
[   21.807249][   T69]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   21.807255][   T69]  ? kobject_put (lib/kobject.c:733)
[   21.807259][   T69]  kasan_report (mm/kasan/report.c:597)
[   21.807265][   T69]  ? kobject_put (lib/kobject.c:733)
[   21.807275][   T69]  kobject_put (lib/kobject.c:733)
[   21.807281][   T69]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   21.807290][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   21.807296][   T69]  ? generic_xdp_install (net/core/dev.c:11630)
[   21.807301][   T69]  ? net_generic (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/net/netns/generic.h:48)
[   21.807315][   T69]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   21.807323][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   21.807329][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   21.807340][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   21.807347][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   21.807355][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   21.807367][   T69]  process_one_work (kernel/workqueue.c:3268)
[   21.807383][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   21.807392][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   21.807399][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   21.807410][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   21.807417][   T69]  kthread (kernel/kthread.c:463)
[   21.807423][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   21.807426][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   21.807432][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   21.807437][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   21.807441][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   21.807445][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   21.807447][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   21.807450][   T69]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   21.827326][   T69] refcount_t: underflow; use-after-free.
| [   21.827560][   T69] WARNING: CPU: 0 PID: 69 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   21.828034][   T69] Modules linked in:
| [   21.828879][   T69] Tainted: [B]=BAD_PAGE
[   21.829099][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   21.829464][   T69] Workqueue: netns cleanup_net
[   21.829759][   T69] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   21.830115][   T69] Code: cc 38 03 80 fb 01 0f 87 29 33 d7 fe 83 e3 01 0f 85 51 ff ff ff c6 05 17 cc 38 03 01 90 48 c7 c7 40 ba 05 97 e8 62 d6 16 ff 90 <0f> 0b 90 90 e9 33 ff ff ff 48 89 df e8 c0 9d a0 ff e9 ba fe ff ff
All code
========
   0:	cc                   	int3
   1:	38 03                	cmp    %al,(%rbx)
   3:	80 fb 01             	cmp    $0x1,%bl
   6:	0f 87 29 33 d7 fe    	ja     0xfffffffffed73335
   c:	83 e3 01             	and    $0x1,%ebx
   f:	0f 85 51 ff ff ff    	jne    0xffffffffffffff66
  15:	c6 05 17 cc 38 03 01 	movb   $0x1,0x338cc17(%rip)        # 0x338cc33
  1c:	90                   	nop
  1d:	48 c7 c7 40 ba 05 97 	mov    $0xffffffff9705ba40,%rdi
  24:	e8 62 d6 16 ff       	call   0xffffffffff16d68b
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	e9 33 ff ff ff       	jmp    0xffffffffffffff66
  33:	48 89 df             	mov    %rbx,%rdi
  36:	e8 c0 9d a0 ff       	call   0xffffffffffa09dfb
  3b:	e9 ba fe ff ff       	jmp    0xfffffffffffffefa

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	e9 33 ff ff ff       	jmp    0xffffffffffffff3c
   9:	48 89 df             	mov    %rbx,%rdi
   c:	e8 c0 9d a0 ff       	call   0xffffffffffa09dd1
  11:	e9 ba fe ff ff       	jmp    0xfffffffffffffed0
[   21.831104][   T69] RSP: 0018:ffffc900004a7a08 EFLAGS: 00010282
[   21.831472][   T69] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   21.831884][   T69] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   21.832310][   T69] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff3000934
[   21.832725][   T69] R10: 0000000000000003 R11: ffffc900004a7580 R12: 0000000000000001
[   21.833150][   T69] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   21.833570][   T69] FS:  0000000000000000(0000) GS:ffff8880d3b08000(0000) knlGS:0000000000000000
[   21.834052][   T69] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   21.834429][   T69] CR2: 000055f223b490f8 CR3: 0000000030b49002 CR4: 0000000000772ef0
[   21.834840][   T69] PKRU: 55555554
[   21.835053][   T69] Call Trace:
[   21.835271][   T69]  <TASK>
[   21.835416][   T69]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   21.835707][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   21.836024][   T69]  ? generic_xdp_install (net/core/dev.c:11630)
[   21.836325][   T69]  ? net_generic (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/net/netns/generic.h:48)
[   21.836617][   T69]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   21.836895][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   21.837172][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   21.837487][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   21.837766][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   21.838046][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   21.838353][   T69]  process_one_work (kernel/workqueue.c:3268)
[   21.838657][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   21.838939][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   21.839231][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   21.839507][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   21.839787][   T69]  kthread (kernel/kthread.c:463)
[   21.839997][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   21.840286][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   21.840564][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   21.840853][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   21.841133][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   21.841423][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   21.841696][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)


Finger prints:
print_report:kasan_report:kobject_put:netdev_run_todo:ops_undo_list
refcount_warn_saturate:netdev_run_todo:ops_undo_list:cleanup_net:process_one_work