======================================
| xx__-> [   34.590141][   T72] ==================================================================
| [   34.590444][   T72] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   34.590698][   T72] Read of size 1 at addr ffff8880081316ac by task kworker/u16:1/72
| [   34.590933][   T72]
[   34.591019][   T72] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   34.591022][   T72] Workqueue: netns cleanup_net
[   34.591032][   T72] Call Trace:
[   34.591034][   T72]  <TASK>
[   34.591036][   T72]  dump_stack_lvl (lib/dump_stack.c:123)
[   34.591042][   T72]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   34.591051][   T72]  ? kobject_put (lib/kobject.c:733)
[   34.591055][   T72]  print_report (mm/kasan/report.c:483)
[   34.591059][   T72]  ? kobject_put (lib/kobject.c:733)
[   34.591062][   T72]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   34.591066][   T72]  ? kobject_put (lib/kobject.c:733)
[   34.591069][   T72]  kasan_report (mm/kasan/report.c:597)
[   34.591073][   T72]  ? kobject_put (lib/kobject.c:733)
[   34.591079][   T72]  kobject_put (lib/kobject.c:733)
[   34.591083][   T72]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   34.591089][   T72]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   34.591093][   T72]  ? generic_xdp_install (net/core/dev.c:11630)
[   34.591100][   T72]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   34.591109][   T72]  ? netns_get (net/core/net_namespace.c:223)
[   34.591112][   T72]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   34.591117][   T72]  cleanup_net (net/core/net_namespace.c:698)
[   34.591120][   T72]  ? net_passive_dec (net/core/net_namespace.c:660)
[   34.591124][   T72]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   34.591132][   T72]  process_one_work (kernel/workqueue.c:3268)
[   34.591141][   T72]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   34.591147][   T72]  ? assign_work (kernel/workqueue.c:1206)
[   34.591151][   T72]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   34.591156][   T72]  ? rescuer_thread (kernel/workqueue.c:3373)
[   34.591160][   T72]  kthread (kernel/kthread.c:463)
[   34.591165][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   34.591167][   T72]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   34.591172][   T72]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   34.591178][   T72]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   34.591181][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   34.591185][   T72]  ret_from_fork (arch/x86/kernel/process.c:164)
[   34.591188][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   34.591191][   T72]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   34.609067][   T72] refcount_t: underflow; use-after-free.
| [   34.609269][   T72] WARNING: CPU: 0 PID: 72 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   34.609556][   T72] Modules linked in: nft_redir nft_chain_nat nf_nat nf_conntrack_netlink nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables veth
| [   34.610858][   T72] Tainted: [B]=BAD_PAGE
[   34.610976][   T72] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   34.611172][   T72] Workqueue: netns cleanup_net
[   34.611334][   T72] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   34.611547][   T72] 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 b6 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 b6 	mov    $0xffffffffb665dea0,%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
[   34.612123][   T72] RSP: 0018:ffffc900004d7a08 EFLAGS: 00010282
[   34.612329][   T72] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   34.612573][   T72] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   34.612815][   T72] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff6dfe220
[   34.613054][   T72] R10: 0000000000000003 R11: ffffc900004d7580 R12: 0000000000000001
[   34.613287][   T72] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   34.613535][   T72] FS:  0000000000000000(0000) GS:ffff88807ddec000(0000) knlGS:0000000000000000
[   34.613814][   T72] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   34.614010][   T72] CR2: 00007f3e6a541000 CR3: 000000000cb35005 CR4: 0000000000772ef0
[   34.614244][   T72] PKRU: 55555554
[   34.614368][   T72] Call Trace:
[   34.614497][   T72]  <TASK>
[   34.614580][   T72]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   34.614756][   T72]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   34.614919][   T72]  ? generic_xdp_install (net/core/dev.c:11630)
[   34.615082][   T72]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   34.615237][   T72]  ? netns_get (net/core/net_namespace.c:223)
[   34.615400][   T72]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   34.615557][   T72]  cleanup_net (net/core/net_namespace.c:698)
[   34.615714][   T72]  ? net_passive_dec (net/core/net_namespace.c:660)
[   34.615876][   T72]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   34.616040][   T72]  process_one_work (kernel/workqueue.c:3268)
[   34.616199][   T72]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   34.616365][   T72]  ? assign_work (kernel/workqueue.c:1206)
[   34.616522][   T72]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   34.616679][   T72]  ? rescuer_thread (kernel/workqueue.c:3373)
[   34.616843][   T72]  kthread (kernel/kthread.c:463)
[   34.616964][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   34.617117][   T72]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   34.617276][   T72]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   34.617438][   T72]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   34.617591][   T72]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   34.617755][   T72]  ret_from_fork (arch/x86/kernel/process.c:164)
[   34.617911][   T72]  ? 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