======================================
| xx__-> [   16.829013][   T70] ==================================================================
| [   16.829490][   T70] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   16.829878][   T70] Read of size 1 at addr ffff88800a579694 by task kworker/u16:1/70
| [   16.830178][   T70]
[   16.830330][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   16.830334][   T70] Workqueue: netns cleanup_net
[   16.830343][   T70] Call Trace:
[   16.830346][   T70]  <TASK>
[   16.830349][   T70]  dump_stack_lvl (lib/dump_stack.c:123)
[   16.830356][   T70]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   16.830365][   T70]  ? kobject_put (lib/kobject.c:733)
[   16.830369][   T70]  print_report (mm/kasan/report.c:483)
[   16.830372][   T70]  ? kobject_put (lib/kobject.c:733)
[   16.830375][   T70]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   16.830379][   T70]  ? kobject_put (lib/kobject.c:733)
[   16.830382][   T70]  kasan_report (mm/kasan/report.c:597)
[   16.830386][   T70]  ? kobject_put (lib/kobject.c:733)
[   16.830391][   T70]  kobject_put (lib/kobject.c:733)
[   16.830395][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   16.830402][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   16.830406][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   16.830413][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   16.830417][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   16.830419][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   16.830424][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   16.830427][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   16.830431][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   16.830437][   T70]  process_one_work (kernel/workqueue.c:3268)
[   16.830445][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   16.830450][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   16.830454][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   16.830459][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   16.830462][   T70]  kthread (kernel/kthread.c:463)
[   16.830466][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.830468][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   16.830475][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   16.830484][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   16.830488][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.830493][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   16.830498][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.830500][   T70]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   16.851878][   T70] refcount_t: underflow; use-after-free.
| [   16.852094][   T70] WARNING: CPU: 3 PID: 70 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   16.852431][   T70] Modules linked in: veth
| [   16.853031][   T70] Tainted: [B]=BAD_PAGE
[   16.853175][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   16.853406][   T70] Workqueue: netns cleanup_net
[   16.853611][   T70] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   16.853847][   T70] 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 65 a1 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 65 a1             	lea    -0x5f(%rbp),%esp
  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
[   16.854497][   T70] RSP: 0018:ffffc900004b7a08 EFLAGS: 00010282
[   16.854724][   T70] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   16.855012][   T70] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   16.855295][   T70] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff43fe134
[   16.855588][   T70] R10: 0000000000000003 R11: ffffc900004b7580 R12: 0000000000000001
[   16.855871][   T70] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   16.856160][   T70] FS:  0000000000000000(0000) GS:ffff88808d390000(0000) knlGS:0000000000000000
[   16.856484][   T70] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   16.856717][   T70] CR2: 00007f2ef8edd100 CR3: 0000000004c9f006 CR4: 0000000000772ef0
[   16.857033][   T70] PKRU: 55555554
[   16.857268][   T70] Call Trace:
[   16.857412][   T70]  <TASK>
[   16.857519][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   16.857712][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   16.857927][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   16.858127][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   16.858317][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   16.858506][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   16.858708][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   16.858894][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   16.859085][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   16.859274][   T70]  process_one_work (kernel/workqueue.c:3268)
[   16.859461][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   16.859657][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   16.859850][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   16.860035][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   16.860244][   T70]  kthread (kernel/kthread.c:463)
[   16.860387][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.860574][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   16.860764][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   16.860974][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   16.861174][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.861351][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   16.861551][   T70]  ? 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