======================================
| [  144.884785][   T68] ==================================================================
| [  144.885062][   T68] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [  144.885310][   T68] Read of size 1 at addr ffff8880076c969c by task kworker/u16:1/68
| [  144.885544][   T68]
[  144.885644][   T68] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  144.885647][   T68] Workqueue: netns cleanup_net
[  144.885655][   T68] Call Trace:
[  144.885657][   T68]  <TASK>
[  144.885661][   T68]  dump_stack_lvl (lib/dump_stack.c:123)
[  144.885666][   T68]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[  144.885675][   T68]  ? kobject_put (lib/kobject.c:733)
[  144.885679][   T68]  print_report (mm/kasan/report.c:483)
[  144.885682][   T68]  ? kobject_put (lib/kobject.c:733)
[  144.885685][   T68]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[  144.885689][   T68]  ? kobject_put (lib/kobject.c:733)
[  144.885691][   T68]  kasan_report (mm/kasan/report.c:597)
[  144.885695][   T68]  ? kobject_put (lib/kobject.c:733)
[  144.885700][   T68]  kobject_put (lib/kobject.c:733)
[  144.885704][   T68]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[  144.885711][   T68]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[  144.885714][   T68]  ? generic_xdp_install (net/core/dev.c:11630)
[  144.885720][   T68]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[  144.885725][   T68]  ? netns_get (net/core/net_namespace.c:223)
[  144.885728][   T68]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[  144.885733][   T68]  cleanup_net (net/core/net_namespace.c:698)
[  144.885737][   T68]  ? net_passive_dec (net/core/net_namespace.c:660)
[  144.885742][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  144.885751][   T68]  process_one_work (kernel/workqueue.c:3268)
[  144.885762][   T68]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[  144.885768][   T68]  ? assign_work (kernel/workqueue.c:1206)
[  144.885773][   T68]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[  144.885779][   T68]  ? rescuer_thread (kernel/workqueue.c:3373)
[  144.885783][   T68]  kthread (kernel/kthread.c:463)
[  144.885788][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  144.885791][   T68]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[  144.885797][   T68]  ? __lock_release (kernel/locking/lockdep.c:5536)
[  144.885803][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  144.885806][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  144.885810][   T68]  ret_from_fork (arch/x86/kernel/process.c:164)
[  144.885813][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  144.885816][   T68]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [  144.903880][   T68] refcount_t: underflow; use-after-free.
| [  144.904077][   T68] WARNING: CPU: 0 PID: 68 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [  144.904536][   T68] Modules linked in: sch_netem
| [  144.905086][   T68] Tainted: [B]=BAD_PAGE
[  144.905227][   T68] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  144.905437][   T68] Workqueue: netns cleanup_net
[  144.905616][   T68] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[  144.905837][   T68] 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 c5 b8 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 c5 b8 	mov    $0xffffffffb8c58d60,%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
[  144.906434][   T68] RSP: 0018:ffffc90000497a08 EFLAGS: 00010282
[  144.906653][   T68] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[  144.906906][   T68] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[  144.907174][   T68] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff72c2934
[  144.907426][   T68] R10: 0000000000000003 R11: ffffc90000497580 R12: 0000000000000001
[  144.907669][   T68] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[  144.907919][   T68] FS:  0000000000000000(0000) GS:ffff88807b784000(0000) knlGS:0000000000000000
[  144.908220][   T68] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  144.908431][   T68] CR2: 0000559a2e18b990 CR3: 000000000c690004 CR4: 0000000000772ef0
[  144.908675][   T68] PKRU: 55555554
[  144.908885][   T68] Call Trace:
[  144.909009][   T68]  <TASK>
[  144.909102][   T68]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[  144.909375][   T68]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[  144.909547][   T68]  ? generic_xdp_install (net/core/dev.c:11630)
[  144.909714][   T68]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[  144.909884][   T68]  ? netns_get (net/core/net_namespace.c:223)
[  144.910047][   T68]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[  144.910224][   T68]  cleanup_net (net/core/net_namespace.c:698)
[  144.910389][   T68]  ? net_passive_dec (net/core/net_namespace.c:660)
[  144.910554][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  144.910727][   T68]  process_one_work (kernel/workqueue.c:3268)
[  144.910892][   T68]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[  144.911059][   T68]  ? assign_work (kernel/workqueue.c:1206)
[  144.911237][   T68]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[  144.911406][   T68]  ? rescuer_thread (kernel/workqueue.c:3373)
[  144.911569][   T68]  kthread (kernel/kthread.c:463)
[  144.911695][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  144.911864][   T68]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[  144.912030][   T68]  ? __lock_release (kernel/locking/lockdep.c:5536)
[  144.912206][   T68]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[  144.912378][   T68]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[  144.912542][   T68]  ret_from_fork (arch/x86/kernel/process.c:164)
[  144.912706][   T68]  ? 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