======================================
| xx__-> [   50.491821][   T70] ==================================================================
| [   50.492158][   T70] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   50.492448][   T70] Read of size 1 at addr ffff8880051896ac by task kworker/u16:1/70
| [   50.492697][   T70]
[   50.492789][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   50.492792][   T70] Workqueue: netns cleanup_net
[   50.492806][   T70] Call Trace:
[   50.492810][   T70]  <TASK>
[   50.492814][   T70]  dump_stack_lvl (lib/dump_stack.c:123)
[   50.492823][   T70]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   50.492842][   T70]  ? kobject_put (lib/kobject.c:733)
[   50.492847][   T70]  print_report (mm/kasan/report.c:483)
[   50.492850][   T70]  ? kobject_put (lib/kobject.c:733)
[   50.492853][   T70]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   50.492857][   T70]  ? kobject_put (lib/kobject.c:733)
[   50.492860][   T70]  kasan_report (mm/kasan/report.c:597)
[   50.492865][   T70]  ? kobject_put (lib/kobject.c:733)
[   50.492871][   T70]  kobject_put (lib/kobject.c:733)
[   50.492874][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   50.492880][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   50.492884][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   50.492891][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   50.492901][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   50.492905][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   50.492910][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   50.492915][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   50.492919][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   50.492933][   T70]  process_one_work (kernel/workqueue.c:3268)
[   50.492946][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   50.492951][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   50.492955][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   50.492961][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   50.492965][   T70]  kthread (kernel/kthread.c:463)
[   50.492970][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   50.492973][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   50.492991][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   50.493000][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   50.493003][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   50.493007][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   50.493010][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   50.493013][   T70]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   50.513520][   T70] refcount_t: underflow; use-after-free.
| [   50.513735][   T70] WARNING: CPU: 0 PID: 70 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   50.514067][   T70] Modules linked in: inet_diag nft_tproxy nf_tproxy_ipv6 nf_tproxy_ipv4 nf_defrag_ipv6 nf_defrag_ipv4 nf_tables veth
| [   50.514891][   T70] Tainted: [B]=BAD_PAGE
[   50.515027][   T70] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   50.515248][   T70] Workqueue: netns cleanup_net
[   50.515437][   T70] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   50.515661][   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 e5 85 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 e5 85 	mov    $0xffffffff85e5dea0,%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
[   50.516277][   T70] RSP: 0018:ffffc900004b7a08 EFLAGS: 00010282
[   50.516501][   T70] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   50.516760][   T70] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   50.517032][   T70] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff0cfe220
[   50.517290][   T70] R10: 0000000000000003 R11: ffffc900004b7580 R12: 0000000000000001
[   50.517542][   T70] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   50.517814][   T70] FS:  0000000000000000(0000) GS:ffff8880a8bec000(0000) knlGS:0000000000000000
[   50.518114][   T70] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   50.518327][   T70] CR2: 00007ffcc973ca08 CR3: 000000000d91d002 CR4: 0000000000772ef0
[   50.518586][   T70] PKRU: 55555554
[   50.518715][   T70] Call Trace:
[   50.518853][   T70]  <TASK>
[   50.518950][   T70]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   50.519124][   T70]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   50.519296][   T70]  ? generic_xdp_install (net/core/dev.c:11630)
[   50.519469][   T70]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   50.519642][   T70]  ? netns_get (net/core/net_namespace.c:223)
[   50.519821][   T70]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   50.519993][   T70]  cleanup_net (net/core/net_namespace.c:698)
[   50.520172][   T70]  ? net_passive_dec (net/core/net_namespace.c:660)
[   50.520343][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   50.520520][   T70]  process_one_work (kernel/workqueue.c:3268)
[   50.520698][   T70]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   50.520876][   T70]  ? assign_work (kernel/workqueue.c:1206)
[   50.521051][   T70]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   50.521222][   T70]  ? rescuer_thread (kernel/workqueue.c:3373)
[   50.521390][   T70]  kthread (kernel/kthread.c:463)
[   50.521519][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   50.521689][   T70]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   50.521873][   T70]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   50.522052][   T70]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   50.522222][   T70]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   50.522389][   T70]  ret_from_fork (arch/x86/kernel/process.c:164)
[   50.522558][   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