======================================
| [   59.005655][   T71] ==================================================================
| [   59.006104][   T71] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   59.006494][   T71] Read of size 1 at addr ffff888005dd46ac by task kworker/u16:1/71
| [   59.006863][   T71]
[   59.007008][   T71] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   59.007015][   T71] Workqueue: netns cleanup_net
[   59.007028][   T71] Call Trace:
[   59.007033][   T71]  <TASK>
[   59.007039][   T71]  dump_stack_lvl (lib/dump_stack.c:123)
[   59.007056][   T71]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   59.007066][   T71]  ? kobject_put (lib/kobject.c:733)
[   59.007072][   T71]  print_report (mm/kasan/report.c:483)
[   59.007077][   T71]  ? kobject_put (lib/kobject.c:733)
[   59.007081][   T71]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   59.007087][   T71]  ? kobject_put (lib/kobject.c:733)
[   59.007091][   T71]  kasan_report (mm/kasan/report.c:597)
[   59.007098][   T71]  ? kobject_put (lib/kobject.c:733)
[   59.007106][   T71]  kobject_put (lib/kobject.c:733)
[   59.007111][   T71]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   59.007119][   T71]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   59.007124][   T71]  ? generic_xdp_install (net/core/dev.c:11630)
[   59.007135][   T71]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   59.007145][   T71]  ? netns_get (net/core/net_namespace.c:223)
[   59.007150][   T71]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   59.007158][   T71]  cleanup_net (net/core/net_namespace.c:698)
[   59.007163][   T71]  ? net_passive_dec (net/core/net_namespace.c:660)
[   59.007169][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   59.007179][   T71]  process_one_work (kernel/workqueue.c:3268)
[   59.007192][   T71]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   59.007201][   T71]  ? assign_work (kernel/workqueue.c:1206)
[   59.007207][   T71]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   59.007216][   T71]  ? rescuer_thread (kernel/workqueue.c:3373)
[   59.007221][   T71]  kthread (kernel/kthread.c:463)
[   59.007228][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   59.007231][   T71]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   59.007240][   T71]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   59.007248][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   59.007253][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   59.007258][   T71]  ret_from_fork (arch/x86/kernel/process.c:164)
[   59.007262][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   59.007266][   T71]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   59.036517][   T71] refcount_t: underflow; use-after-free.
| [   59.036802][   T71] WARNING: CPU: 2 PID: 71 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   59.037239][   T71] Modules linked in: nft_quota nf_tables
| [   59.038953][   T71] Tainted: [B]=BAD_PAGE
[   59.039245][   T71] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   59.039667][   T71] Workqueue: netns cleanup_net
[   59.040056][   T71] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   59.040488][   T71] 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 65 ad 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 65 ad 	mov    $0xffffffffad65dea0,%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
[   59.041609][   T71] RSP: 0018:ffffc900004c7a08 EFLAGS: 00010282
[   59.042016][   T71] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   59.042494][   T71] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   59.042956][   T71] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff5bfe220
[   59.043417][   T71] R10: 0000000000000003 R11: ffffc900004c7580 R12: 0000000000000001
[   59.043872][   T71] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   59.044334][   T71] FS:  0000000000000000(0000) GS:ffff888086eec000(0000) knlGS:0000000000000000
[   59.044852][   T71] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   59.045347][   T71] CR2: 00007f1523153810 CR3: 000000000fb35005 CR4: 0000000000772ef0
[   59.045844][   T71] PKRU: 55555554
[   59.046149][   T71] Call Trace:
[   59.046445][   T71]  <TASK>
[   59.046678][   T71]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   59.047131][   T71]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   59.047496][   T71]  ? generic_xdp_install (net/core/dev.c:11630)
[   59.047845][   T71]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   59.048186][   T71]  ? netns_get (net/core/net_namespace.c:223)
[   59.048539][   T71]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   59.048877][   T71]  cleanup_net (net/core/net_namespace.c:698)
[   59.049249][   T71]  ? net_passive_dec (net/core/net_namespace.c:660)
[   59.049600][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   59.050034][   T71]  process_one_work (kernel/workqueue.c:3268)
[   59.050380][   T71]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   59.050650][   T71]  ? assign_work (kernel/workqueue.c:1206)
[   59.050905][   T71]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   59.051182][   T71]  ? rescuer_thread (kernel/workqueue.c:3373)
[   59.051479][   T71]  kthread (kernel/kthread.c:463)
[   59.051688][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   59.051936][   T71]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   59.052202][   T71]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   59.052497][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   59.052744][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   59.053121][   T71]  ret_from_fork (arch/x86/kernel/process.c:164)
[   59.053345][   T71]  ? 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