======================================
| [   30.565465][   T70] ==================================================================
| [   30.565815][   T70] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   30.566116][   T70] Read of size 1 at addr ffff888008a946ac by task kworker/u16:1/70
| [   30.566368][   T70]
[   30.566460][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   30.566463][   T70] Workqueue: netns cleanup_net
[   30.566471][   T70] Call Trace:
[   30.566474][   T70]  <TASK>
[   30.566478][   T70]  dump_stack_lvl (lib/dump_stack.c:123)
[   30.566486][   T70]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   30.566497][   T70]  ? kobject_put (lib/kobject.c:733)
[   30.566502][   T70]  print_report (mm/kasan/report.c:483)
[   30.566506][   T70]  ? kobject_put (lib/kobject.c:733)
[   30.566509][   T70]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   30.566513][   T70]  ? kobject_put (lib/kobject.c:733)
[   30.566516][   T70]  kasan_report (mm/kasan/report.c:597)
[   30.566521][   T70]  ? kobject_put (lib/kobject.c:733)
[   30.566527][   T70]  kobject_put (lib/kobject.c:733)
[   30.566531][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   30.566537][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   30.566540][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   30.566547][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   30.566556][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   30.566559][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   30.566564][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   30.566567][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   30.566571][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   30.566578][   T70]  process_one_work (kernel/workqueue.c:3268)
[   30.566586][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   30.566592][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   30.566596][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   30.566602][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   30.566605][   T70]  kthread (kernel/kthread.c:463)
[   30.566610][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.566612][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   30.566620][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   30.566627][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   30.566630][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.566633][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   30.566636][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.566639][   T70]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   30.587515][   T70] refcount_t: underflow; use-after-free.
| [   30.587739][   T70] WARNING: CPU: 3 PID: 70 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   30.588146][   T70] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel 8021q veth br_netfilter bridge stp llc
| [   30.589065][   T70] Tainted: [B]=BAD_PAGE
[   30.589207][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   30.589490][   T70] Workqueue: netns cleanup_net
[   30.589755][   T70] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   30.590059][   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 25 a3 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 25 a3 	mov    $0xffffffffa325dea0,%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
[   30.590802][   T70] RSP: 0018:ffffc900004b7a08 EFLAGS: 00010282
[   30.591086][   T70] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   30.591360][   T70] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   30.591632][   T70] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff477e220
[   30.591905][   T70] R10: 0000000000000003 R11: ffffc900004b7580 R12: 0000000000000001
[   30.592179][   T70] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   30.592464][   T70] FS:  0000000000000000(0000) GS:ffff88809136c000(0000) knlGS:0000000000000000
[   30.592834][   T70] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   30.593204][   T70] CR2: 00007fa9dc2f7000 CR3: 000000002ab35001 CR4: 0000000000772ef0
[   30.593497][   T70] PKRU: 55555554
[   30.593645][   T70] Call Trace:
[   30.593813][   T70]  <TASK>
[   30.594022][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   30.594224][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   30.594431][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   30.594640][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   30.594842][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   30.595023][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   30.595206][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   30.595423][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   30.595713][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   30.595915][   T70]  process_one_work (kernel/workqueue.c:3268)
[   30.596102][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   30.596305][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   30.596612][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   30.596799][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   30.597011][   T70]  kthread (kernel/kthread.c:463)
[   30.597160][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.597373][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   30.597706][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   30.597942][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   30.598169][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   30.598404][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   30.598734][   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