======================================
| [   29.207688][   T12] ==================================================================
| [   29.208116][   T12] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   29.208547][   T12] Read of size 1 at addr ffff88800a4cc69c by task kworker/u16:0/12
| [   29.208934][   T12]
[   29.209092][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   29.209097][   T12] Workqueue: netns cleanup_net
[   29.209108][   T12] Call Trace:
[   29.209111][   T12]  <TASK>
[   29.209115][   T12]  dump_stack_lvl (lib/dump_stack.c:123)
[   29.209123][   T12]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   29.209132][   T12]  ? kobject_put (lib/kobject.c:733)
[   29.209138][   T12]  print_report (mm/kasan/report.c:483)
[   29.209143][   T12]  ? kobject_put (lib/kobject.c:733)
[   29.209147][   T12]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   29.209152][   T12]  ? kobject_put (lib/kobject.c:733)
[   29.209156][   T12]  kasan_report (mm/kasan/report.c:597)
[   29.209162][   T12]  ? kobject_put (lib/kobject.c:733)
[   29.209171][   T12]  kobject_put (lib/kobject.c:733)
[   29.209176][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   29.209184][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   29.209189][   T12]  ? unregister_netdevice_many (net/core/dev.c:12241)
[   29.209194][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[   29.209198][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   29.209213][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   29.209222][   T12]  ? netns_get (net/core/net_namespace.c:223)
[   29.209227][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   29.209236][   T12]  cleanup_net (net/core/net_namespace.c:698)
[   29.209243][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[   29.209250][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   29.209260][   T12]  process_one_work (kernel/workqueue.c:3268)
[   29.209274][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   29.209284][   T12]  ? assign_work (kernel/workqueue.c:1206)
[   29.209292][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   29.209302][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[   29.209308][   T12]  kthread (kernel/kthread.c:463)
[   29.209315][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   29.209319][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   29.209328][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   29.209334][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   29.209339][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   29.209345][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[   29.209350][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   29.209354][   T12]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   29.242236][   T12] refcount_t: underflow; use-after-free.
| [   29.242884][   T12] WARNING: CPU: 1 PID: 12 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   29.243363][   T12] Modules linked in:
| [   29.244211][   T12] Tainted: [B]=BAD_PAGE
[   29.244433][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   29.244859][   T12] Workqueue: netns cleanup_net
[   29.245171][   T12] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   29.245528][   T12] Code: a2 b5 02 80 fb 01 0f 87 db 6e d8 fe 83 e3 01 0f 85 51 ff ff ff c6 05 c2 a2 b5 02 01 90 48 c7 c7 60 a8 05 89 e8 72 c3 17 ff 90 <0f> 0b 90 90 e9 33 ff ff ff 48 89 df e8 20 69 a0 ff e9 ba fe ff ff
All code
========
   0:	a2 b5 02 80 fb 01 0f 	movabs %al,0xdb870f01fb8002b5
   7:	87 db 
   9:	6e                   	outsb  %ds:(%rsi),(%dx)
   a:	d8 fe                	fdivr  %st(6),%st
   c:	83 e3 01             	and    $0x1,%ebx
   f:	0f 85 51 ff ff ff    	jne    0xffffffffffffff66
  15:	c6 05 c2 a2 b5 02 01 	movb   $0x1,0x2b5a2c2(%rip)        # 0x2b5a2de
  1c:	90                   	nop
  1d:	48 c7 c7 60 a8 05 89 	mov    $0xffffffff8905a860,%rdi
  24:	e8 72 c3 17 ff       	call   0xffffffffff17c39b
  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 20 69 a0 ff       	call   0xffffffffffa0695b
  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 20 69 a0 ff       	call   0xffffffffffa06931
  11:	e9 ba fe ff ff       	jmp    0xfffffffffffffed0
[   29.246512][   T12] RSP: 0018:ffffc900000c7a08 EFLAGS: 00010282
[   29.246852][   T12] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   29.247243][   T12] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   29.247645][   T12] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff133e134
[   29.248047][   T12] R10: 0000000000000003 R11: ffffc900000c7580 R12: 0000000000000001
[   29.248451][   T12] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   29.248810][   T12] FS:  0000000000000000(0000) GS:ffff8880ab401000(0000) knlGS:0000000000000000
[   29.249254][   T12] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   29.249577][   T12] CR2: 000055612ecb5dec CR3: 000000000cb61005 CR4: 0000000000772ef0
[   29.249951][   T12] PKRU: 55555554
[   29.250140][   T12] Call Trace:
[   29.250332][   T12]  <TASK>
[   29.250463][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   29.250736][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   29.251012][   T12]  ? unregister_netdevice_many (net/core/dev.c:12241)
[   29.251448][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[   29.251708][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   29.251973][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   29.252209][   T12]  ? netns_get (net/core/net_namespace.c:223)
[   29.252624][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   29.252884][   T12]  cleanup_net (net/core/net_namespace.c:698)
[   29.253135][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[   29.253398][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   29.253816][   T12]  process_one_work (kernel/workqueue.c:3268)
[   29.254089][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   29.254358][   T12]  ? assign_work (kernel/workqueue.c:1206)
[   29.254621][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   29.255043][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[   29.255290][   T12]  kthread (kernel/kthread.c:463)
[   29.255486][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   29.255736][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   29.256185][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   29.256461][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   29.256725][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   29.256983][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[   29.257423][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)


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