======================================
| xx__-> [  104.505484][   T12] ==================================================================
| [  104.505802][   T12] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [  104.506047][   T12] Read of size 1 at addr ffff88800838c69c by task kworker/u16:0/12
| [  104.506272][   T12]
[  104.506363][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  104.506365][   T12] Workqueue: netns cleanup_net
[  104.506373][   T12] Call Trace:
[  104.506375][   T12]  <TASK>
[  104.506378][   T12]  dump_stack_lvl (lib/dump_stack.c:123)
[  104.506385][   T12]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[  104.506397][   T12]  ? kobject_put (lib/kobject.c:733)
[  104.506400][   T12]  print_report (mm/kasan/report.c:483)
[  104.506404][   T12]  ? kobject_put (lib/kobject.c:733)
[  104.506407][   T12]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[  104.506410][   T12]  ? kobject_put (lib/kobject.c:733)
[  104.506413][   T12]  kasan_report (mm/kasan/report.c:597)
[  104.506417][   T12]  ? kobject_put (lib/kobject.c:733)
[  104.506422][   T12]  kobject_put (lib/kobject.c:733)
[  104.506425][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[  104.506433][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[  104.506436][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[  104.506442][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[  104.506447][   T12]  ? netns_get (net/core/net_namespace.c:223)
[  104.506450][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[  104.506457][   T12]  cleanup_net (net/core/net_namespace.c:698)
[  104.506461][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[  104.506465][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  104.506475][   T12]  process_one_work (kernel/workqueue.c:3268)
[  104.506487][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[  104.506495][   T12]  ? assign_work (kernel/workqueue.c:1206)
[  104.506500][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[  104.506506][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[  104.506510][   T12]  kthread (kernel/kthread.c:463)
[  104.506514][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  104.506517][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[  104.506522][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[  104.506528][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  104.506532][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  104.506535][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[  104.506538][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  104.506541][   T12]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [  104.523440][   T12] refcount_t: underflow; use-after-free.
| [  104.523664][   T12] WARNING: CPU: 0 PID: 12 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [  104.524001][   T12] Modules linked in:
| [  104.524467][   T12] Tainted: [B]=BAD_PAGE
[  104.524590][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  104.524798][   T12] Workqueue: netns cleanup_net
[  104.524959][   T12] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[  104.525155][   T12] Code: 32 b8 02 80 fb 01 0f 87 cb 8b d9 fe 83 e3 01 0f 85 51 ff ff ff c6 05 e5 32 b8 02 01 90 48 c7 c7 60 8d 65 b1 e8 42 c1 18 ff 90 <0f> 0b 90 90 e9 33 ff ff ff 48 89 df e8 b0 63 a1 ff e9 ba fe ff ff
All code
========
   0:	32 b8 02 80 fb 01    	xor    0x1fb8002(%rax),%bh
   6:	0f 87 cb 8b d9 fe    	ja     0xfffffffffed98bd7
   c:	83 e3 01             	and    $0x1,%ebx
   f:	0f 85 51 ff ff ff    	jne    0xffffffffffffff66
  15:	c6 05 e5 32 b8 02 01 	movb   $0x1,0x2b832e5(%rip)        # 0x2b83301
  1c:	90                   	nop
  1d:	48 c7 c7 60 8d 65 b1 	mov    $0xffffffffb1658d60,%rdi
  24:	e8 42 c1 18 ff       	call   0xffffffffff18c16b
  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 b0 63 a1 ff       	call   0xffffffffffa163eb
  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 b0 63 a1 ff       	call   0xffffffffffa163c1
  11:	e9 ba fe ff ff       	jmp    0xfffffffffffffed0
[  104.525702][   T12] RSP: 0018:ffffc900000c7a08 EFLAGS: 00010282
[  104.525906][   T12] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[  104.526140][   T12] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[  104.526366][   T12] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff6402934
[  104.526588][   T12] R10: 0000000000000003 R11: ffffc900000c7580 R12: 0000000000000001
[  104.526830][   T12] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[  104.527053][   T12] FS:  0000000000000000(0000) GS:ffff888082d84000(0000) knlGS:0000000000000000
[  104.527317][   T12] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  104.527506][   T12] CR2: 00007f14108b5d40 CR3: 0000000001e3a005 CR4: 0000000000772ef0
[  104.527837][   T12] PKRU: 55555554
[  104.527955][   T12] Call Trace:
[  104.528067][   T12]  <TASK>
[  104.528146][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[  104.528387][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[  104.528628][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[  104.528792][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[  104.528941][   T12]  ? netns_get (net/core/net_namespace.c:223)
[  104.529173][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[  104.529407][   T12]  cleanup_net (net/core/net_namespace.c:698)
[  104.529646][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[  104.529803][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  104.529961][   T12]  process_one_work (kernel/workqueue.c:3268)
[  104.530116][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[  104.530269][   T12]  ? assign_work (kernel/workqueue.c:1206)
[  104.530417][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[  104.530568][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[  104.530723][   T12]  kthread (kernel/kthread.c:463)
[  104.530933][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  104.531173][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[  104.531326][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[  104.531476][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  104.531714][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  104.531872][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[  104.532022][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)


Finger prints:
refcount_warn_saturate:netdev_run_todo:ops_undo_list:cleanup_net:process_one_work
print_report:kasan_report:kobject_put:netdev_run_todo:ops_undo_list