======================================
| xx__-> [  117.032039][   T68] ==================================================================
| [  117.032328][   T68] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [  117.032581][   T68] Read of size 1 at addr ffff888008ba16c4 by task kworker/u16:1/68
| [  117.032812][   T68]
[  117.032903][   T68] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  117.032906][   T68] Workqueue: netns cleanup_net
[  117.032915][   T68] Call Trace:
[  117.032918][   T68]  <TASK>
[  117.032920][   T68]  dump_stack_lvl (lib/dump_stack.c:123)
[  117.032926][   T68]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[  117.032936][   T68]  ? kobject_put (lib/kobject.c:733)
[  117.032940][   T68]  print_report (mm/kasan/report.c:483)
[  117.032944][   T68]  ? kobject_put (lib/kobject.c:733)
[  117.032950][   T68]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[  117.032953][   T68]  ? kobject_put (lib/kobject.c:733)
[  117.032956][   T68]  kasan_report (mm/kasan/report.c:597)
[  117.032960][   T68]  ? kobject_put (lib/kobject.c:733)
[  117.032966][   T68]  kobject_put (lib/kobject.c:733)
[  117.032969][   T68]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[  117.032976][   T68]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[  117.032979][   T68]  ? generic_xdp_install (net/core/dev.c:11630)
[  117.032982][   T68]  ? net_generic (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/net/netns/generic.h:48)
[  117.032992][   T68]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[  117.032997][   T68]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[  117.033000][   T68]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[  117.033006][   T68]  cleanup_net (net/core/net_namespace.c:698)
[  117.033011][   T68]  ? net_passive_dec (net/core/net_namespace.c:660)
[  117.033015][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  117.033028][   T68]  process_one_work (kernel/workqueue.c:3268)
[  117.033039][   T68]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[  117.033045][   T68]  ? assign_work (kernel/workqueue.c:1206)
[  117.033049][   T68]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[  117.033055][   T68]  ? rescuer_thread (kernel/workqueue.c:3373)
[  117.033059][   T68]  kthread (kernel/kthread.c:463)
[  117.033063][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  117.033066][   T68]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[  117.033073][   T68]  ? __lock_release (kernel/locking/lockdep.c:5536)
[  117.033078][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  117.033083][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  117.033087][   T68]  ret_from_fork (arch/x86/kernel/process.c:164)
[  117.033089][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  117.033092][   T68]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [  117.051741][   T68] refcount_t: underflow; use-after-free.
| [  117.051992][   T68] WARNING: CPU: 1 PID: 68 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [  117.052289][   T68] Modules linked in:
| [  117.052776][   T68] Tainted: [B]=BAD_PAGE
[  117.052895][   T68] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  117.053108][   T68] Workqueue: netns cleanup_net
[  117.053288][   T68] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[  117.053491][   T68] 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 25 b5 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 25 b5 	mov    $0xffffffffb525ba40,%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
[  117.054057][   T68] RSP: 0018:ffffc90000497a08 EFLAGS: 00010282
[  117.054275][   T68] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[  117.054513][   T68] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[  117.054748][   T68] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff6c40934
[  117.054992][   T68] R10: 0000000000000003 R11: ffffc90000497580 R12: 0000000000000001
[  117.055240][   T68] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[  117.055474][   T68] FS:  0000000000000000(0000) GS:ffff8880af588000(0000) knlGS:0000000000000000
[  117.055749][   T68] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  117.055958][   T68] CR2: 00007efe63747000 CR3: 0000000072949006 CR4: 0000000000772ef0
[  117.056206][   T68] PKRU: 55555554
[  117.056325][   T68] Call Trace:
[  117.056443][   T68]  <TASK>
[  117.056526][   T68]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[  117.056687][   T68]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[  117.056853][   T68]  ? generic_xdp_install (net/core/dev.c:11630)
[  117.057020][   T68]  ? net_generic (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/net/netns/generic.h:48)
[  117.057185][   T68]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[  117.057365][   T68]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[  117.057522][   T68]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[  117.057673][   T68]  cleanup_net (net/core/net_namespace.c:698)
[  117.057824][   T68]  ? net_passive_dec (net/core/net_namespace.c:660)
[  117.057989][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  117.058155][   T68]  process_one_work (kernel/workqueue.c:3268)
[  117.058328][   T68]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[  117.058481][   T68]  ? assign_work (kernel/workqueue.c:1206)
[  117.058632][   T68]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[  117.058784][   T68]  ? rescuer_thread (kernel/workqueue.c:3373)
[  117.058938][   T68]  kthread (kernel/kthread.c:463)
[  117.059063][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  117.059225][   T68]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[  117.059382][   T68]  ? __lock_release (kernel/locking/lockdep.c:5536)
[  117.059534][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  117.059685][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  117.059836][   T68]  ret_from_fork (arch/x86/kernel/process.c:164)
[  117.059994][   T68]  ? 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