======================================
| xx__-> [   24.236749][   T70] ==================================================================
| [   24.237052][   T70] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   24.237327][   T70] Read of size 1 at addr ffff88800759969c by task kworker/u16:1/70
| [   24.237573][   T70]
[   24.237669][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   24.237672][   T70] Workqueue: netns cleanup_net
[   24.237682][   T70] Call Trace:
[   24.237687][   T70]  <TASK>
[   24.237689][   T70]  dump_stack_lvl (lib/dump_stack.c:123)
[   24.237697][   T70]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   24.237706][   T70]  ? kobject_put (lib/kobject.c:733)
[   24.237710][   T70]  print_report (mm/kasan/report.c:483)
[   24.237713][   T70]  ? kobject_put (lib/kobject.c:733)
[   24.237716][   T70]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   24.237719][   T70]  ? kobject_put (lib/kobject.c:733)
[   24.237722][   T70]  kasan_report (mm/kasan/report.c:597)
[   24.237726][   T70]  ? kobject_put (lib/kobject.c:733)
[   24.237731][   T70]  kobject_put (lib/kobject.c:733)
[   24.237734][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   24.237742][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   24.237746][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   24.237752][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   24.237757][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   24.237762][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   24.237767][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   24.237771][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   24.237775][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   24.237785][   T70]  process_one_work (kernel/workqueue.c:3268)
[   24.237796][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   24.237802][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   24.237806][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   24.237812][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   24.237816][   T70]  kthread (kernel/kthread.c:463)
[   24.237821][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   24.237824][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   24.237830][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   24.237836][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   24.237839][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   24.237843][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   24.237846][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   24.237849][   T70]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   24.258082][   T70] refcount_t: underflow; use-after-free.
| [   24.258325][   T70] WARNING: CPU: 0 PID: 70 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   24.258653][   T70] Modules linked in:
| [   24.259227][   T70] Tainted: [B]=BAD_PAGE
[   24.259371][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   24.259603][   T70] Workqueue: netns cleanup_net
[   24.259823][   T70] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   24.260063][   T70] 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 a5 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 a5 	mov    $0xffffffffa5658d60,%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
[   24.260718][   T70] RSP: 0018:ffffc900004b7a08 EFLAGS: 00010282
[   24.260956][   T70] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   24.261230][   T70] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   24.261505][   T70] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff4c02934
[   24.261802][   T70] R10: 0000000000000003 R11: ffffc900004b7580 R12: 0000000000000001
[   24.262083][   T70] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   24.262361][   T70] FS:  0000000000000000(0000) GS:ffff888088f84000(0000) knlGS:0000000000000000
[   24.262695][   T70] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   24.262927][   T70] CR2: 00007f4f1a248920 CR3: 000000000a80c001 CR4: 0000000000772ef0
[   24.263211][   T70] PKRU: 55555554
[   24.263358][   T70] Call Trace:
[   24.263486][   T70]  <TASK>
[   24.263573][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   24.263761][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   24.263942][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   24.264117][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   24.264302][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   24.264482][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   24.264675][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   24.264867][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   24.265054][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   24.265241][   T70]  process_one_work (kernel/workqueue.c:3268)
[   24.265514][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   24.265710][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   24.265898][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   24.266074][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   24.266340][   T70]  kthread (kernel/kthread.c:463)
[   24.266481][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   24.266673][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   24.266869][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   24.267056][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   24.267235][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   24.267429][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   24.267615][   T70]  ? 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