======================================
| xx__-> [   14.513792][   T12] ==================================================================
| [   14.514165][   T12] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   14.514462][   T12] Read of size 1 at addr ffff888001fdc694 by task kworker/u16:0/12
| [   14.514759][   T12]
[   14.514869][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   14.514874][   T12] Workqueue: netns cleanup_net
[   14.514882][   T12] Call Trace:
[   14.514885][   T12]  <TASK>
[   14.514888][   T12]  dump_stack_lvl (lib/dump_stack.c:123)
[   14.514894][   T12]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   14.514903][   T12]  ? kobject_put (lib/kobject.c:733)
[   14.514907][   T12]  print_report (mm/kasan/report.c:483)
[   14.514910][   T12]  ? kobject_put (lib/kobject.c:733)
[   14.514913][   T12]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   14.514917][   T12]  ? kobject_put (lib/kobject.c:733)
[   14.514920][   T12]  kasan_report (mm/kasan/report.c:597)
[   14.514924][   T12]  ? kobject_put (lib/kobject.c:733)
[   14.514929][   T12]  kobject_put (lib/kobject.c:733)
[   14.514933][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   14.514939][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   14.514943][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[   14.514949][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   14.514954][   T12]  ? netns_get (net/core/net_namespace.c:223)
[   14.514956][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   14.514961][   T12]  cleanup_net (net/core/net_namespace.c:698)
[   14.514964][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[   14.514968][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   14.514975][   T12]  process_one_work (kernel/workqueue.c:3268)
[   14.514983][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   14.514988][   T12]  ? assign_work (kernel/workqueue.c:1206)
[   14.514992][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   14.514997][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[   14.515001][   T12]  kthread (kernel/kthread.c:463)
[   14.515004][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   14.515006][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   14.515013][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   14.515019][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   14.515022][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   14.515025][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[   14.515028][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   14.515030][   T12]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   14.538226][   T12] refcount_t: underflow; use-after-free.
| [   14.538519][   T12] WARNING: CPU: 0 PID: 12 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   14.539641][   T12] Modules linked in: veth
| [   14.540681][   T12] Tainted: [B]=BAD_PAGE
[   14.540910][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   14.541243][   T12] Workqueue: netns cleanup_net
[   14.541517][   T12] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   14.541875][   T12] 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 e5 9e 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                   	lea    (bad),%esp
  22:	e5 9e                	in     $0x9e,%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
[   14.543030][   T12] RSP: 0018:ffffc900000c7a08 EFLAGS: 00010282
[   14.543490][   T12] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   14.543842][   T12] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   14.544256][   T12] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff3efe134
[   14.544672][   T12] R10: 0000000000000003 R11: ffffc900000c7580 R12: 0000000000000001
[   14.545047][   T12] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   14.545466][   T12] FS:  0000000000000000(0000) GS:ffff88808fc10000(0000) knlGS:0000000000000000
[   14.545945][   T12] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   14.546287][   T12] CR2: 00007fd1f5345000 CR3: 0000000009453004 CR4: 0000000000772ef0
[   14.546710][   T12] PKRU: 55555554
[   14.546921][   T12] Call Trace:
[   14.547114][   T12]  <TASK>
[   14.547260][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   14.547716][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   14.548015][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[   14.548335][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   14.548672][   T12]  ? netns_get (net/core/net_namespace.c:223)
[   14.549085][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   14.549373][   T12]  cleanup_net (net/core/net_namespace.c:698)
[   14.549564][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[   14.549724][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   14.549887][   T12]  process_one_work (kernel/workqueue.c:3268)
[   14.550064][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   14.550231][   T12]  ? assign_work (kernel/workqueue.c:1206)
[   14.550421][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   14.550639][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[   14.550821][   T12]  kthread (kernel/kthread.c:463)
[   14.550968][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   14.551128][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   14.551325][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   14.551490][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   14.551738][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   14.552021][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[   14.552294][   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