======================================
| [   66.468729][   T12] ==================================================================
| [   66.469019][   T12] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   66.469277][   T12] Read of size 1 at addr ffff88800f5096c4 by task kworker/u16:0/12
| [   66.469512][   T12]
[   66.469616][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   66.469619][   T12] Workqueue: netns cleanup_net
[   66.469627][   T12] Call Trace:
[   66.469631][   T12]  <TASK>
[   66.469633][   T12]  dump_stack_lvl (lib/dump_stack.c:123)
[   66.469643][   T12]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   66.469656][   T12]  ? kobject_put (lib/kobject.c:733)
[   66.469660][   T12]  print_report (mm/kasan/report.c:483)
[   66.469664][   T12]  ? kobject_put (lib/kobject.c:733)
[   66.469667][   T12]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   66.469670][   T12]  ? kobject_put (lib/kobject.c:733)
[   66.469673][   T12]  kasan_report (mm/kasan/report.c:597)
[   66.469677][   T12]  ? kobject_put (lib/kobject.c:733)
[   66.469682][   T12]  kobject_put (lib/kobject.c:733)
[   66.469686][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   66.469691][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   66.469695][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[   66.469698][   T12]  ? net_generic (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/net/netns/generic.h:48)
[   66.469706][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   66.469712][   T12]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   66.469715][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   66.469721][   T12]  cleanup_net (net/core/net_namespace.c:698)
[   66.469725][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[   66.469730][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   66.469740][   T12]  process_one_work (kernel/workqueue.c:3268)
[   66.469752][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   66.469758][   T12]  ? assign_work (kernel/workqueue.c:1206)
[   66.469762][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   66.469768][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[   66.469771][   T12]  kthread (kernel/kthread.c:463)
[   66.469775][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   66.469780][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   66.469784][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   66.469788][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   66.469792][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   66.469795][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[   66.469798][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   66.469801][   T12]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   66.488209][   T12] refcount_t: underflow; use-after-free.
| [   66.488427][   T12] WARNING: CPU: 0 PID: 12 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   66.488770][   T12] Modules linked in:
| [   66.489325][   T12] Tainted: [B]=BAD_PAGE
[   66.489459][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   66.489702][   T12] Workqueue: netns cleanup_net
[   66.489881][   T12] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   66.490121][   T12] 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 8f 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 8f 	mov    $0xffffffff8f65ba40,%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
[   66.490741][   T12] RSP: 0018:ffffc900000c7a08 EFLAGS: 00010282
[   66.490966][   T12] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   66.491241][   T12] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   66.491490][   T12] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff20c0934
[   66.491760][   T12] R10: 0000000000000003 R11: ffffc900000c7580 R12: 0000000000000001
[   66.492043][   T12] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   66.492296][   T12] FS:  0000000000000000(0000) GS:ffff8880db508000(0000) knlGS:0000000000000000
[   66.492615][   T12] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   66.492840][   T12] CR2: 00007f82e7eb7810 CR3: 000000003a349004 CR4: 0000000000772ef0
[   66.493122][   T12] PKRU: 55555554
[   66.493263][   T12] Call Trace:
[   66.493397][   T12]  <TASK>
[   66.493498][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   66.493695][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   66.493876][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[   66.494073][   T12]  ? net_generic (./include/linux/rcupdate.h:341 ./include/linux/rcupdate.h:897 ./include/net/netns/generic.h:48)
[   66.494262][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   66.494440][   T12]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   66.494632][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   66.494815][   T12]  cleanup_net (net/core/net_namespace.c:698)
[   66.495095][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[   66.495279][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   66.495452][   T12]  process_one_work (kernel/workqueue.c:3268)
[   66.495652][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   66.495826][   T12]  ? assign_work (kernel/workqueue.c:1206)
[   66.496009][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   66.496287][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[   66.496462][   T12]  kthread (kernel/kthread.c:463)
[   66.496596][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   66.496777][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   66.496954][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   66.497169][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   66.497340][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   66.497513][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[   66.497701][   T12]  ? 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