======================================
| xx__-> [   65.271392][   T12] ==================================================================
| [   65.271786][   T12] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   65.272160][   T12] Read of size 1 at addr ffff88800e8dc69c by task kworker/u16:0/12
| [   65.272522][   T12]
[   65.272657][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   65.272661][   T12] Workqueue: netns cleanup_net
[   65.272671][   T12] Call Trace:
[   65.272674][   T12]  <TASK>
[   65.272677][   T12]  dump_stack_lvl (lib/dump_stack.c:123)
[   65.272685][   T12]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   65.272694][   T12]  ? kobject_put (lib/kobject.c:733)
[   65.272699][   T12]  print_report (mm/kasan/report.c:483)
[   65.272704][   T12]  ? kobject_put (lib/kobject.c:733)
[   65.272707][   T12]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   65.272713][   T12]  ? kobject_put (lib/kobject.c:733)
[   65.272718][   T12]  kasan_report (mm/kasan/report.c:597)
[   65.272724][   T12]  ? kobject_put (lib/kobject.c:733)
[   65.272734][   T12]  kobject_put (lib/kobject.c:733)
[   65.272740][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   65.272747][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   65.272753][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[   65.272764][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   65.272773][   T12]  ? netns_get (net/core/net_namespace.c:223)
[   65.272778][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   65.272788][   T12]  cleanup_net (net/core/net_namespace.c:698)
[   65.272794][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[   65.272802][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   65.272811][   T12]  process_one_work (kernel/workqueue.c:3268)
[   65.272824][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   65.272835][   T12]  ? assign_work (kernel/workqueue.c:1206)
[   65.272843][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   65.272853][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[   65.272860][   T12]  kthread (kernel/kthread.c:463)
[   65.272866][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   65.272871][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   65.272876][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   65.272883][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   65.272889][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   65.272896][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[   65.272900][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   65.272905][   T12]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   65.301835][   T12] refcount_t: underflow; use-after-free.
| [   65.302032][   T12] WARNING: CPU: 2 PID: 12 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   65.302326][   T12] Modules linked in: xt_mark nft_compat nf_tables
| [   65.302937][   T12] Tainted: [B]=BAD_PAGE
[   65.303073][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   65.303285][   T12] Workqueue: netns cleanup_net
[   65.303468][   T12] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   65.303697][   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 25 87 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 25 87 	mov    $0xffffffff87258d60,%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
[   65.304267][   T12] RSP: 0018:ffffc900000c7a08 EFLAGS: 00010282
[   65.304489][   T12] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   65.304739][   T12] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   65.304994][   T12] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff0f82934
[   65.305240][   T12] R10: 0000000000000003 R11: ffffc900000c7580 R12: 0000000000000001
[   65.305493][   T12] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   65.305747][   T12] FS:  0000000000000000(0000) GS:ffff8880ad284000(0000) knlGS:0000000000000000
[   65.306034][   T12] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   65.306245][   T12] CR2: 00007f94e3e49000 CR3: 000000000bf59004 CR4: 0000000000772ef0
[   65.306497][   T12] PKRU: 55555554
[   65.306640][   T12] Call Trace:
[   65.306776][   T12]  <TASK>
[   65.306875][   T12]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   65.307050][   T12]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   65.307230][   T12]  ? generic_xdp_install (net/core/dev.c:11630)
[   65.307407][   T12]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   65.307588][   T12]  ? netns_get (net/core/net_namespace.c:223)
[   65.307761][   T12]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   65.307936][   T12]  cleanup_net (net/core/net_namespace.c:698)
[   65.308108][   T12]  ? net_passive_dec (net/core/net_namespace.c:660)
[   65.308280][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   65.308461][   T12]  process_one_work (kernel/workqueue.c:3268)
[   65.308832][   T12]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   65.309008][   T12]  ? assign_work (kernel/workqueue.c:1206)
[   65.309181][   T12]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   65.309354][   T12]  ? rescuer_thread (kernel/workqueue.c:3373)
[   65.309538][   T12]  kthread (kernel/kthread.c:463)
[   65.309767][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   65.309940][   T12]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   65.310110][   T12]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   65.310289][   T12]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   65.310461][   T12]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   65.310730][   T12]  ret_from_fork (arch/x86/kernel/process.c:164)
[   65.310903][   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