======================================
| [  779.569938][   T69] ==================================================================
| [  779.570287][   T69] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [  779.570556][   T69] Read of size 1 at addr ffff8880085296c4 by task kworker/u16:1/69
| [  779.570794][   T69]
[  779.570897][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  779.570902][   T69] Workqueue: netns cleanup_net
[  779.570917][   T69] Call Trace:
[  779.570921][   T69]  <TASK>
[  779.570924][   T69]  dump_stack_lvl (lib/dump_stack.c:123)
[  779.570931][   T69]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[  779.570943][   T69]  ? kobject_put (lib/kobject.c:733)
[  779.570949][   T69]  print_report (mm/kasan/report.c:483)
[  779.570952][   T69]  ? kobject_put (lib/kobject.c:733)
[  779.570955][   T69]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[  779.570959][   T69]  ? kobject_put (lib/kobject.c:733)
[  779.570962][   T69]  kasan_report (mm/kasan/report.c:597)
[  779.570967][   T69]  ? kobject_put (lib/kobject.c:733)
[  779.570972][   T69]  kobject_put (lib/kobject.c:733)
[  779.570976][   T69]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[  779.570982][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[  779.570986][   T69]  ? generic_xdp_install (net/core/dev.c:11630)
[  779.570989][   T69]  ? net_generic (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/net/netns/generic.h:48)
[  779.571001][   T69]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[  779.571007][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[  779.571010][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[  779.571016][   T69]  cleanup_net (net/core/net_namespace.c:698)
[  779.571020][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[  779.571025][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  779.571036][   T69]  process_one_work (kernel/workqueue.c:3268)
[  779.571047][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[  779.571052][   T69]  ? assign_work (kernel/workqueue.c:1206)
[  779.571057][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[  779.571063][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[  779.571067][   T69]  kthread (kernel/kthread.c:463)
[  779.571071][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  779.571074][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[  779.571083][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[  779.571089][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  779.571092][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  779.571096][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[  779.571098][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  779.571102][   T69]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [  779.590621][   T69] refcount_t: underflow; use-after-free.
| [  779.590840][   T69] WARNING: CPU: 2 PID: 69 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [  779.591138][   T69] Modules linked in: xfrm_user xt_policy nft_compat nf_tables
| [  779.591784][   T69] Tainted: [B]=BAD_PAGE
[  779.591923][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  779.592134][   T69] Workqueue: netns cleanup_net
[  779.592318][   T69] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[  779.592534][   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 65 93 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 65 93 	mov    $0xffffffff9365ba40,%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
[  779.593122][   T69] RSP: 0018:ffffc900004a7a08 EFLAGS: 00010282
[  779.593338][   T69] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[  779.593600][   T69] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[  779.593868][   T69] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff28c0934
[  779.594119][   T69] R10: 0000000000000003 R11: ffffc900004a7580 R12: 0000000000000001
[  779.594372][   T69] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[  779.594626][   T69] FS:  0000000000000000(0000) GS:ffff8880d7608000(0000) knlGS:0000000000000000
[  779.594917][   T69] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  779.595136][   T69] CR2: 00007ffd78e58d58 CR3: 000000000db6f006 CR4: 0000000000772ef0
[  779.595394][   T69] PKRU: 55555554
[  779.595533][   T69] Call Trace:
[  779.595680][   T69]  <TASK>
[  779.595789][   T69]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[  779.595967][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[  779.596148][   T69]  ? generic_xdp_install (net/core/dev.c:11630)
[  779.596342][   T69]  ? net_generic (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/net/netns/generic.h:48)
[  779.596520][   T69]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[  779.596706][   T69]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[  779.596878][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[  779.597050][   T69]  cleanup_net (net/core/net_namespace.c:698)
[  779.597225][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[  779.597401][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  779.597586][   T69]  process_one_work (kernel/workqueue.c:3268)
[  779.597782][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[  779.597955][   T69]  ? assign_work (kernel/workqueue.c:1206)
[  779.598132][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[  779.598309][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[  779.598481][   T69]  kthread (kernel/kthread.c:463)
[  779.598616][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  779.598795][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[  779.598971][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[  779.599146][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  779.599325][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  779.599501][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[  779.599674][   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