======================================
| xx__-> [   38.710343][   T71] ==================================================================
| [   38.710653][   T71] BUG: KASAN: slab-use-after-free in kobject_put (lib/kobject.c:733)
| [   38.710914][   T71] Read of size 1 at addr ffff888007bf96ac by task kworker/u16:1/71
| [   38.711145][   T71]
[   38.711239][   T71] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   38.711243][   T71] Workqueue: netns cleanup_net
[   38.711249][   T71] Call Trace:
[   38.711252][   T71]  <TASK>
[   38.711254][   T71]  dump_stack_lvl (lib/dump_stack.c:123)
[   38.711260][   T71]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   38.711269][   T71]  ? kobject_put (lib/kobject.c:733)
[   38.711273][   T71]  print_report (mm/kasan/report.c:483)
[   38.711278][   T71]  ? kobject_put (lib/kobject.c:733)
[   38.711281][   T71]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   38.711285][   T71]  ? kobject_put (lib/kobject.c:733)
[   38.711288][   T71]  kasan_report (mm/kasan/report.c:597)
[   38.711292][   T71]  ? kobject_put (lib/kobject.c:733)
[   38.711298][   T71]  kobject_put (lib/kobject.c:733)
[   38.711302][   T71]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   38.711308][   T71]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   38.711312][   T71]  ? generic_xdp_install (net/core/dev.c:11630)
[   38.711319][   T71]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   38.711327][   T71]  ? netns_get (net/core/net_namespace.c:223)
[   38.711330][   T71]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   38.711335][   T71]  cleanup_net (net/core/net_namespace.c:698)
[   38.711339][   T71]  ? net_passive_dec (net/core/net_namespace.c:660)
[   38.711343][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   38.711350][   T71]  process_one_work (kernel/workqueue.c:3268)
[   38.711359][   T71]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   38.711365][   T71]  ? assign_work (kernel/workqueue.c:1206)
[   38.711369][   T71]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   38.711375][   T71]  ? rescuer_thread (kernel/workqueue.c:3373)
[   38.711378][   T71]  kthread (kernel/kthread.c:463)
[   38.711383][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   38.711386][   T71]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   38.711393][   T71]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   38.711400][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   38.711402][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   38.711406][   T71]  ret_from_fork (arch/x86/kernel/process.c:164)
[   38.711409][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   38.711412][   T71]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
| [   38.730019][   T71] refcount_t: underflow; use-after-free.
| [   38.730221][   T71] WARNING: CPU: 2 PID: 71 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   38.730536][   T71] Modules linked in: nft_redir nft_chain_nat nf_nat nf_conntrack_netlink nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables veth
| [   38.731987][   T71] Tainted: [B]=BAD_PAGE
[   38.732182][   T71] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   38.732456][   T71] Workqueue: netns cleanup_net
[   38.732671][   T71] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   38.732927][   T71] 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 94 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 94 	mov    $0xffffffff94e5dea0,%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
[   38.733490][   T71] RSP: 0018:ffffc900004c7a08 EFLAGS: 00010282
[   38.733719][   T71] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   38.733991][   T71] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   38.734251][   T71] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff2afe220
[   38.734519][   T71] R10: 0000000000000003 R11: ffffc900004c7580 R12: 0000000000000001
[   38.734778][   T71] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   38.735030][   T71] FS:  0000000000000000(0000) GS:ffff888099aec000(0000) knlGS:0000000000000000
[   38.735313][   T71] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   38.735527][   T71] CR2: 00007fa47fa8a000 CR3: 000000003d535002 CR4: 0000000000772ef0
[   38.735787][   T71] PKRU: 55555554
[   38.735925][   T71] Call Trace:
[   38.736067][   T71]  <TASK>
[   38.736170][   T71]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   38.736353][   T71]  ? dev_ingress_queue_create (net/core/dev.c:12299)
[   38.736529][   T71]  ? generic_xdp_install (net/core/dev.c:11630)
[   38.736719][   T71]  ops_undo_list (net/core/net_namespace.c:190 net/core/net_namespace.c:248)
[   38.736894][   T71]  ? netns_get (net/core/net_namespace.c:223)
[   38.737068][   T71]  ? cleanup_net (./include/linux/list.h:191 net/core/net_namespace.c:693)
[   38.737239][   T71]  cleanup_net (net/core/net_namespace.c:698)
[   38.737411][   T71]  ? net_passive_dec (net/core/net_namespace.c:660)
[   38.737584][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   38.737772][   T71]  process_one_work (kernel/workqueue.c:3268)
[   38.737954][   T71]  ? pwq_dec_nr_in_flight (kernel/workqueue.c:3165)
[   38.738129][   T71]  ? assign_work (kernel/workqueue.c:1206)
[   38.738300][   T71]  worker_thread (kernel/workqueue.c:3340 kernel/workqueue.c:3427)
[   38.738492][   T71]  ? rescuer_thread (kernel/workqueue.c:3373)
[   38.738694][   T71]  kthread (kernel/kthread.c:463)
[   38.738837][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   38.739019][   T71]  ? ret_from_fork (arch/x86/kernel/process.c:157)
[   38.739194][   T71]  ? __lock_release (kernel/locking/lockdep.c:5536)
[   38.739379][   T71]  ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:751)
[   38.739561][   T71]  ? kthread_is_per_cpu (kernel/kthread.c:412)
[   38.739739][   T71]  ret_from_fork (arch/x86/kernel/process.c:164)
[   38.739922][   T71]  ? 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