======================================
| xx__-> [   30.483953][   T70] ==================================================================
| [   30.484313][   T70] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   30.484627][   T70] Read of size 1 at addr ffff888008d9c6ac by task kworker/u16:1/70
| [   30.484905][   T70]
[   30.485019][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   30.485023][   T70] Workqueue: netns cleanup_net
[   30.485037][   T70] Call Trace:
[   30.485041][   T70]  <TASK>
[   30.485044][   T70]  dump_stack_lvl (lib/dump_stack.c:123)
[   30.485052][   T70]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   30.485064][   T70]  ? kobject_put (lib/kobject.c:733)
[   30.485068][   T70]  print_report (mm/kasan/report.c:483)
[   30.485072][   T70]  ? kobject_put (lib/kobject.c:733)
[   30.485075][   T70]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   30.485079][   T70]  ? kobject_put (lib/kobject.c:733)
[   30.485082][   T70]  kasan_report (mm/kasan/report.c:597)
[   30.485087][   T70]  ? kobject_put (lib/kobject.c:733)
[   30.485092][   T70]  kobject_put (lib/kobject.c:733)
[   30.485096][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   30.485103][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   30.485107][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   30.485114][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   30.485123][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   30.485126][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   30.485131][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   30.485134][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   30.485138][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   30.485147][   T70]  process_one_work (kernel/workqueue.c:3268)
[   30.485158][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   30.485163][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   30.485167][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   30.485173][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   30.485176][   T70]  kthread (kernel/kthread.c:463)
[   30.485182][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.485184][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   30.485196][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   30.485205][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   30.485208][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.485211][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   30.485214][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.485217][   T70]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   30.507179][   T70] refcount_t: underflow; use-after-free.
| [   30.507416][   T70] WARNING: CPU: 3 PID: 70 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   30.507827][   T70] Modules linked in: nf_conntrack_netlink tcp_diag inet_diag nf_conntrack_ftp nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables veth
| [   30.508699][   T70] Tainted: [B]=BAD_PAGE
[   30.508824][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   30.509025][   T70] Workqueue: netns cleanup_net
[   30.509196][   T70] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   30.509407][   T70] 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 a5 96 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 a5 96 	mov    $0xffffffff96a5dea0,%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
[   30.510109][   T70] RSP: 0000:ffffc900004b7a08 EFLAGS: 00010282
[   30.510443][   T70] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   30.510823][   T70] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   30.511200][   T70] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff2e7e220
[   30.511575][   T70] R10: 0000000000000003 R11: ffffc900004b7580 R12: 0000000000000001
[   30.511959][   T70] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   30.512348][   T70] FS:  0000000000000000(0000) GS:ffff88809db6c000(0000) knlGS:0000000000000000
[   30.512811][   T70] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   30.513136][   T70] CR2: 00007fdb68d5f49c CR3: 0000000028735004 CR4: 0000000000772ef0
[   30.513517][   T70] PKRU: 55555554
[   30.513721][   T70] Call Trace:
[   30.513921][   T70]  <TASK>
[   30.514054][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   30.514321][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   30.514569][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   30.514835][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   30.515084][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   30.515466][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   30.515716][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   30.515972][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   30.516223][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   30.516666][   T70]  process_one_work (kernel/workqueue.c:3268)
[   30.516933][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   30.517184][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   30.517439][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   30.517697][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   30.517947][   T70]  kthread (kernel/kthread.c:463)
[   30.518138][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.518389][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   30.518656][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   30.518914][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   30.519167][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.519390][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   30.519595][   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