======================================
| [   40.036073][   T69] ==================================================================
| [   40.036482][   T69] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   40.036886][   T69] Read of size 1 at addr ffff88800caa96ac by task kworker/u16:1/69
| [   40.037223][   T69]
[   40.037346][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   40.037349][   T69] Workqueue: netns cleanup_net
[   40.037357][   T69] Call Trace:
[   40.037359][   T69]  <TASK>
[   40.037363][   T69]  dump_stack_lvl (lib/dump_stack.c:123)
[   40.037371][   T69]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   40.037383][   T69]  ? kobject_put (lib/kobject.c:733)
[   40.037388][   T69]  print_report (mm/kasan/report.c:483)
[   40.037392][   T69]  ? kobject_put (lib/kobject.c:733)
[   40.037395][   T69]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   40.037399][   T69]  ? kobject_put (lib/kobject.c:733)
[   40.037403][   T69]  kasan_report (mm/kasan/report.c:597)
[   40.037407][   T69]  ? kobject_put (lib/kobject.c:733)
[   40.037417][   T69]  kobject_put (lib/kobject.c:733)
[   40.037423][   T69]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   40.037432][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   40.037437][   T69]  ? generic_xdp_install (net/core/dev.c:11630)
[   40.037443][   T69]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   40.037452][   T69]  ? netns_get (net/core/net_namespace.c:223)
[   40.037455][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   40.037460][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   40.037464][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   40.037468][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   40.037474][   T69]  process_one_work (kernel/workqueue.c:3268)
[   40.037482][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   40.037487][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   40.037491][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   40.037497][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   40.037500][   T69]  kthread (kernel/kthread.c:463)
[   40.037504][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   40.037506][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   40.037511][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   40.037517][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   40.037520][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   40.037523][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   40.037526][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   40.037529][   T69]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   40.062101][   T69] refcount_t: underflow; use-after-free.
| [   40.062348][   T69] WARNING: CPU: 3 PID: 69 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   40.062859][   T69] Modules linked in: xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_compat nf_tables x_tables inet_diag ipip veth
| [   40.063948][   T69] Tainted: [B]=BAD_PAGE
[   40.064097][   T69] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   40.064341][   T69] Workqueue: netns cleanup_net
[   40.064565][   T69] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   40.064959][   T69] Code: 83 90 02 80 fb 01 0f 87 95 6b d6 fe 83 e3 01 0f 85 51 ff ff ff c6 05 b1 83 90 02 01 90 48 c7 c7 a0 de e5 a4 e8 c2 8b 15 ff 90 <0f> 0b 90 90 e9 33 ff ff ff 48 89 df e8 f0 34 a1 ff e9 ba fe ff ff
All code
========
   0:	83 90 02 80 fb 01 0f 	adcl   $0xf,0x1fb8002(%rax)
   7:	87 95 6b d6 fe 83    	xchg   %edx,-0x7c012995(%rbp)
   d:	e3 01                	jrcxz  0x10
   f:	0f 85 51 ff ff ff    	jne    0xffffffffffffff66
  15:	c6 05 b1 83 90 02 01 	movb   $0x1,0x29083b1(%rip)        # 0x29083cd
  1c:	90                   	nop
  1d:	48 c7 c7 a0 de e5 a4 	mov    $0xffffffffa4e5dea0,%rdi
  24:	e8 c2 8b 15 ff       	call   0xffffffffff158beb
  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 f0 34 a1 ff       	call   0xffffffffffa1352b
  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 f0 34 a1 ff       	call   0xffffffffffa13501
  11:	e9 ba fe ff ff       	jmp    0xfffffffffffffed0
[   40.065815][   T69] RSP: 0000:ffffc900004a7a08 EFLAGS: 00010282
[   40.066138][   T69] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   40.066487][   T69] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   40.066755][   T69] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff4afe220
[   40.067135][   T69] R10: 0000000000000003 R11: ffffc900004a7580 R12: 0000000000000001
[   40.067535][   T69] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   40.067840][   T69] FS:  0000000000000000(0000) GS:ffff88808f76c000(0000) knlGS:0000000000000000
[   40.068147][   T69] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   40.068384][   T69] CR2: 00007ff9ddc20610 CR3: 0000000030935006 CR4: 0000000000772ef0
[   40.068678][   T69] PKRU: 55555554
[   40.068831][   T69] Call Trace:
[   40.068999][   T69]  <TASK>
[   40.069116][   T69]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   40.069322][   T69]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   40.069621][   T69]  ? generic_xdp_install (net/core/dev.c:11630)
[   40.069810][   T69]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   40.070009][   T69]  ? netns_get (net/core/net_namespace.c:223)
[   40.070178][   T69]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   40.070486][   T69]  cleanup_net (net/core/net_namespace.c:698)
[   40.070692][   T69]  ? net_passive_dec (net/core/net_namespace.c:660)
[   40.070885][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   40.071058][   T69]  process_one_work (kernel/workqueue.c:3268)
[   40.071322][   T69]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   40.071508][   T69]  ? assign_work (kernel/workqueue.c:1206)
[   40.071697][   T69]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   40.071976][   T69]  ? rescuer_thread (kernel/workqueue.c:3373)
[   40.072237][   T69]  kthread (kernel/kthread.c:463)
[   40.072389][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   40.072597][   T69]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   40.072825][   T69]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   40.073011][   T69]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   40.073205][   T69]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   40.073388][   T69]  ret_from_fork (arch/x86/kernel/process.c:164)
[   40.073578][   T69]  ? 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