======================================
| [   44.346054][   T71] ==================================================================
| [   44.346385][   T71] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   44.346689][   T71] Read of size 1 at addr ffff8880084596c4 by task kworker/u16:1/71
| [   44.346974][   T71]
[   44.347086][   T71] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   44.347089][   T71] Workqueue: netns cleanup_net
[   44.347098][   T71] Call Trace:
[   44.347100][   T71]  <TASK>
[   44.347102][   T71]  dump_stack_lvl (lib/dump_stack.c:123)
[   44.347109][   T71]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   44.347119][   T71]  ? kobject_put (lib/kobject.c:733)
[   44.347123][   T71]  print_report (mm/kasan/report.c:483)
[   44.347126][   T71]  ? kobject_put (lib/kobject.c:733)
[   44.347129][   T71]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   44.347133][   T71]  ? kobject_put (lib/kobject.c:733)
[   44.347136][   T71]  kasan_report (mm/kasan/report.c:597)
[   44.347140][   T71]  ? kobject_put (lib/kobject.c:733)
[   44.347145][   T71]  kobject_put (lib/kobject.c:733)
[   44.347149][   T71]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   44.347154][   T71]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   44.347158][   T71]  ? generic_xdp_install (net/core/dev.c:11630)
[   44.347164][   T71]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   44.347169][   T71]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   44.347172][   T71]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   44.347178][   T71]  cleanup_net (net/core/net_namespace.c:698)
[   44.347183][   T71]  ? net_passive_dec (net/core/net_namespace.c:660)
[   44.347187][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   44.347195][   T71]  process_one_work (kernel/workqueue.c:3268)
[   44.347205][   T71]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   44.347210][   T71]  ? assign_work (kernel/workqueue.c:1206)
[   44.347214][   T71]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   44.347220][   T71]  ? rescuer_thread (kernel/workqueue.c:3373)
[   44.347224][   T71]  kthread (kernel/kthread.c:463)
[   44.347228][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   44.347230][   T71]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   44.347238][   T71]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   44.347243][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   44.347246][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   44.347250][   T71]  ret_from_fork (arch/x86/kernel/process.c:164)
[   44.347252][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   44.347255][   T71]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   44.370020][   T71] refcount_t: underflow; use-after-free.
| [   44.370213][   T71] WARNING: CPU: 1 PID: 71 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   44.370688][   T71] Modules linked in: act_gact cls_flower sch_ingress vxlan
| [   44.371275][   T71] Tainted: [B]=BAD_PAGE
[   44.371407][   T71] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   44.371594][   T71] Workqueue: netns cleanup_net
[   44.371754][   T71] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   44.371947][   T71] 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 e5 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 e5 93 	mov    $0xffffffff93e5ba40,%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
[   44.372500][   T71] RSP: 0018:ffffc900004c7a08 EFLAGS: 00010282
[   44.372693][   T71] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   44.372922][   T71] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   44.373148][   T71] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff29c0934
[   44.373398][   T71] R10: 0000000000000003 R11: ffffc900004c7580 R12: 0000000000000001
[   44.373620][   T71] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   44.373844][   T71] FS:  0000000000000000(0000) GS:ffff8880d6d88000(0000) knlGS:0000000000000000
[   44.374104][   T71] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   44.374307][   T71] CR2: 00007f8e5dd0b000 CR3: 0000000011149003 CR4: 0000000000772ef0
[   44.374597][   T71] PKRU: 55555554
[   44.374717][   T71] Call Trace:
[   44.374834][   T71]  <TASK>
[   44.374953][   T71]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   44.375125][   T71]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   44.375303][   T71]  ? generic_xdp_install (net/core/dev.c:11630)
[   44.375470][   T71]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   44.375620][   T71]  ? rtnl_net_dumpid_one (net/core/net_namespace.c:223)
[   44.375768][   T71]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   44.375923][   T71]  cleanup_net (net/core/net_namespace.c:698)
[   44.376072][   T71]  ? net_passive_dec (net/core/net_namespace.c:660)
[   44.376220][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   44.376394][   T71]  process_one_work (kernel/workqueue.c:3268)
[   44.376549][   T71]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   44.376704][   T71]  ? assign_work (kernel/workqueue.c:1206)
[   44.376852][   T71]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   44.377001][   T71]  ? rescuer_thread (kernel/workqueue.c:3373)
[   44.377150][   T71]  kthread (kernel/kthread.c:463)
[   44.377267][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   44.377431][   T71]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   44.377580][   T71]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   44.377727][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   44.377881][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   44.378030][   T71]  ret_from_fork (arch/x86/kernel/process.c:164)
[   44.378176][   T71]  ? 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