======================================
| xx__-> [   17.074502][   T69] ==================================================================
| [   17.074856][   T69] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   17.075101][   T69] Read of size 1 at addr ffff8880083a9694 by task kworker/u16:1/69
| [   17.075363][   T69]
[   17.075460][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   17.075463][   T69] Workqueue: netns cleanup_net
[   17.075470][   T69] Call Trace:
[   17.075472][   T69]  <TASK>
[   17.075475][   T69]  dump_stack_lvl (lib/dump_stack.c:123)
[   17.075480][   T69]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   17.075487][   T69]  ? kobject_put (lib/kobject.c:733)
[   17.075491][   T69]  print_report (mm/kasan/report.c:483)
[   17.075494][   T69]  ? kobject_put (lib/kobject.c:733)
[   17.075497][   T69]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   17.075501][   T69]  ? kobject_put (lib/kobject.c:733)
[   17.075504][   T69]  kasan_report (mm/kasan/report.c:597)
[   17.075508][   T69]  ? kobject_put (lib/kobject.c:733)
[   17.075513][   T69]  kobject_put (lib/kobject.c:733)
[   17.075516][   T69]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   17.075521][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   17.075525][   T69]  ? generic_xdp_install (net/core/dev.c:11630)
[   17.075532][   T69]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   17.075536][   T69]  ? netns_get (net/core/net_namespace.c:223)
[   17.075537][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   17.075542][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   17.075545][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   17.075549][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   17.075555][   T69]  process_one_work (kernel/workqueue.c:3268)
[   17.075562][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   17.075567][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   17.075570][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   17.075576][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   17.075579][   T69]  kthread (kernel/kthread.c:463)
[   17.075582][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   17.075584][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   17.075589][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   17.075595][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   17.075598][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   17.075601][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   17.075604][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   17.075606][   T69]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   17.097105][   T69] refcount_t: underflow; use-after-free.
| [   17.097308][   T69] WARNING: CPU: 0 PID: 69 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   17.097635][   T69] Modules linked in: veth
| [   17.098333][   T69] Tainted: [B]=BAD_PAGE
[   17.098510][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   17.098744][   T69] Workqueue: netns cleanup_net
[   17.098915][   T69] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   17.099302][   T69] Code: 48 92 02 80 fb 01 0f 87 cb 7d d9 fe 83 e3 01 0f 85 51 ff ff ff c6 05 75 48 92 02 01 90 48 c7 c7 a0 8d 45 90 e8 42 93 18 ff 90 <0f> 0b 90 90 e9 33 ff ff ff 48 89 df e8 c0 37 a1 ff e9 ba fe ff ff
All code
========
   0:	48 92                	xchg   %rax,%rdx
   2:	02 80 fb 01 0f 87    	add    -0x78f0fe05(%rax),%al
   8:	cb                   	lret
   9:	7d d9                	jge    0xffffffffffffffe4
   b:	fe 83 e3 01 0f 85    	incb   -0x7af0fe1d(%rbx)
  11:	51                   	push   %rcx
  12:	ff                   	(bad)
  13:	ff                   	(bad)
  14:	ff c6                	inc    %esi
  16:	05 75 48 92 02       	add    $0x2924875,%eax
  1b:	01 90 48 c7 c7 a0    	add    %edx,-0x5f3838b8(%rax)
  21:	8d 45 90             	lea    -0x70(%rbp),%eax
  24:	e8 42 93 18 ff       	call   0xffffffffff18936b
  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 37 a1 ff       	call   0xffffffffffa137fb
  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 37 a1 ff       	call   0xffffffffffa137d1
  11:	e9 ba fe ff ff       	jmp    0xfffffffffffffed0
[   17.100082][   T69] RSP: 0018:ffffc900004a7a08 EFLAGS: 00010282
[   17.100369][   T69] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   17.100661][   T69] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   17.101188][   T69] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff21be134
[   17.101599][   T69] R10: 0000000000000003 R11: ffffc900004a7580 R12: 0000000000000001
[   17.101973][   T69] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   17.103979][   T69] FS:  0000000000000000(0000) GS:ffff8880a4010000(0000) knlGS:0000000000000000
[   17.104328][   T69] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   17.104561][   T69] CR2: 00007f88e0e37000 CR3: 00000000051bd002 CR4: 0000000000772ef0
[   17.104887][   T69] PKRU: 55555554
[   17.105011][   T69] Call Trace:
[   17.105131][   T69]  <TASK>
[   17.105224][   T69]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   17.105492][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   17.105675][   T69]  ? generic_xdp_install (net/core/dev.c:11630)
[   17.105840][   T69]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   17.106002][   T69]  ? netns_get (net/core/net_namespace.c:223)
[   17.106255][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   17.106427][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   17.106610][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   17.106778][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   17.107042][   T69]  process_one_work (kernel/workqueue.c:3268)
[   17.107310][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   17.107505][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   17.107691][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   17.107938][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   17.108111][   T69]  kthread (kernel/kthread.c:463)
[   17.108240][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   17.108406][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   17.108604][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   17.108778][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   17.108938][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   17.109122][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   17.109313][   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