======================================
| xx__-> [   16.110856][   T68] ==================================================================
| [   16.111276][   T68] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   16.111605][   T68] Read of size 1 at addr ffff8880056b4694 by task kworker/u16:1/68
| [   16.112064][   T68]
[   16.112190][   T68] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   16.112195][   T68] Workqueue: netns cleanup_net
[   16.112203][   T68] Call Trace:
[   16.112206][   T68]  <TASK>
[   16.112211][   T68]  dump_stack_lvl (lib/dump_stack.c:123)
[   16.112219][   T68]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   16.112228][   T68]  ? kobject_put (lib/kobject.c:733)
[   16.112234][   T68]  print_report (mm/kasan/report.c:483)
[   16.112240][   T68]  ? kobject_put (lib/kobject.c:733)
[   16.112245][   T68]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   16.112250][   T68]  ? kobject_put (lib/kobject.c:733)
[   16.112253][   T68]  kasan_report (mm/kasan/report.c:597)
[   16.112259][   T68]  ? kobject_put (lib/kobject.c:733)
[   16.112266][   T68]  kobject_put (lib/kobject.c:733)
[   16.112270][   T68]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   16.112277][   T68]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   16.112281][   T68]  ? generic_xdp_install (net/core/dev.c:11630)
[   16.112291][   T68]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   16.112297][   T68]  ? netns_get (net/core/net_namespace.c:223)
[   16.112299][   T68]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   16.112306][   T68]  cleanup_net (net/core/net_namespace.c:698)
[   16.112310][   T68]  ? net_passive_dec (net/core/net_namespace.c:660)
[   16.112315][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   16.112323][   T68]  process_one_work (kernel/workqueue.c:3268)
[   16.112332][   T68]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   16.112340][   T68]  ? assign_work (kernel/workqueue.c:1206)
[   16.112348][   T68]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   16.112358][   T68]  ? rescuer_thread (kernel/workqueue.c:3373)
[   16.112365][   T68]  kthread (kernel/kthread.c:463)
[   16.112371][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.112375][   T68]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   16.112381][   T68]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   16.112389][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   16.112394][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.112400][   T68]  ret_from_fork (arch/x86/kernel/process.c:164)
[   16.112404][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.112407][   T68]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   16.142881][   T68] refcount_t: underflow; use-after-free.
| [   16.143257][   T68] WARNING: CPU: 2 PID: 68 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   16.143582][   T68] Modules linked in: veth
| [   16.144325][   T68] Tainted: [B]=BAD_PAGE
[   16.144548][   T68] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   16.144784][   T68] Workqueue: netns cleanup_net
[   16.145028][   T68] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   16.145270][   T68] 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 25 85 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 25 85 e8 42 93    	lea    -0x6cbd177b(%rip),%esp        # 0xffffffff9342e8ac
  27:	18 ff                	sbb    %bh,%bh
  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
[   16.145917][   T68] RSP: 0018:ffffc90000497a08 EFLAGS: 00010282
[   16.146177][   T68] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   16.146515][   T68] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   16.146801][   T68] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff0b7e134
[   16.147109][   T68] R10: 0000000000000003 R11: ffffc90000497580 R12: 0000000000000001
[   16.147404][   T68] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   16.147665][   T68] FS:  0000000000000000(0000) GS:ffff8880af310000(0000) knlGS:0000000000000000
[   16.148021][   T68] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   16.148253][   T68] CR2: 000055cd4179f45c CR3: 0000000009d6f005 CR4: 0000000000772ef0
[   16.148519][   T68] PKRU: 55555554
[   16.148677][   T68] Call Trace:
[   16.148901][   T68]  <TASK>
[   16.149019][   T68]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   16.149214][   T68]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   16.149408][   T68]  ? generic_xdp_install (net/core/dev.c:11630)
[   16.149589][   T68]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   16.149785][   T68]  ? netns_get (net/core/net_namespace.c:223)
[   16.150008][   T68]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   16.150205][   T68]  cleanup_net (net/core/net_namespace.c:698)
[   16.150411][   T68]  ? net_passive_dec (net/core/net_namespace.c:660)
[   16.150620][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   16.150837][   T68]  process_one_work (kernel/workqueue.c:3268)
[   16.151026][   T68]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   16.151205][   T68]  ? assign_work (kernel/workqueue.c:1206)
[   16.151389][   T68]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   16.151572][   T68]  ? rescuer_thread (kernel/workqueue.c:3373)
[   16.151755][   T68]  kthread (kernel/kthread.c:463)
[   16.151974][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.152155][   T68]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   16.152331][   T68]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   16.152522][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   16.152708][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   16.152892][   T68]  ret_from_fork (arch/x86/kernel/process.c:164)
[   16.153078][   T68]  ? 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