======================================
| xx__-> [   18.393158][  T231] ==================================================================
| [   18.393446][  T231] BUG: KASAN: use-after-free in kobject_put (lib/kobject.c:733)
| [   18.393697][  T231] Read of size 1 at addr ffff8880094a868c by task packetdrill/231
| [   18.393938][  T231]
[   18.394034][  T231] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   18.394039][  T231] Call Trace:
[   18.394044][  T231]  <TASK>
[   18.394046][  T231]  dump_stack_lvl (lib/dump_stack.c:123)
[   18.394058][  T231]  print_address_description.constprop.0 (mm/kasan/report.c:379)
[   18.394074][  T231]  ? kobject_put (lib/kobject.c:733)
[   18.394078][  T231]  print_report (mm/kasan/report.c:483)
[   18.394081][  T231]  ? kobject_put (lib/kobject.c:733)
[   18.394084][  T231]  ? kasan_addr_to_slab (./include/linux/mm.h:1245 mm/kasan/../slab.h:191 mm/kasan/common.c:47)
[   18.394088][  T231]  ? kobject_put (lib/kobject.c:733)
[   18.394091][  T231]  kasan_report (mm/kasan/report.c:597)
[   18.394095][  T231]  ? kobject_put (lib/kobject.c:733)
[   18.394100][  T231]  kobject_put (lib/kobject.c:733)
[   18.394103][  T231]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   18.394113][  T231]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   18.394118][  T231]  ? netif_state_change (./include/net/netdev_lock.h:72 ./include/net/netdev_lock.h:80 net/core/dev.c:1577)
[   18.394121][  T231]  ? call_netdevice_notifiers_info (net/core/dev.c:1576)
[   18.394123][  T231]  ? generic_xdp_install (net/core/dev.c:11630)
[   18.394128][  T231]  ? tun_chr_close (drivers/net/tun.c:638 drivers/net/tun.c:3436)
[   18.394142][  T231]  tun_chr_close (./include/net/sock.h:1990 drivers/net/tun.c:643 drivers/net/tun.c:3436)
[   18.394146][  T231]  __fput (fs/file_table.c:468)
[   18.394158][  T231]  fput_close_sync (fs/file_table.c:571)
[   18.394161][  T231]  ? alloc_file_clone (fs/file_table.c:571)
[   18.394165][  T231]  __x64_sys_close (fs/open.c:1592 fs/open.c:1574 fs/open.c:1574)
[   18.394169][  T231]  do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
[   18.394177][  T231]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[   18.394185][  T231] RIP: 0033:0x4901eb
[   18.394195][  T231] Code: 03 00 00 00 0f 05 48 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 c3 78 04 00 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 21 79 04 00 8b 44
All code
========
   0:	03 00                	add    (%rax),%eax
   2:	00 00                	add    %al,(%rax)
   4:	0f 05                	syscall
   6:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   c:	77 41                	ja     0x4f
   e:	c3                   	ret
   f:	48 83 ec 18          	sub    $0x18,%rsp
  13:	89 7c 24 0c          	mov    %edi,0xc(%rsp)
  17:	e8 c3 78 04 00       	call   0x478df
  1c:	8b 7c 24 0c          	mov    0xc(%rsp),%edi
  20:	41 89 c0             	mov    %eax,%r8d
  23:	b8 03 00 00 00       	mov    $0x3,%eax
  28:	0f 05                	syscall
  2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
  30:	77 35                	ja     0x67
  32:	44 89 c7             	mov    %r8d,%edi
  35:	89 44 24 0c          	mov    %eax,0xc(%rsp)
  39:	e8 21 79 04 00       	call   0x4795f
  3e:	8b                   	.byte 0x8b
  3f:	44                   	rex.R

Code starting with the faulting instruction
===========================================
   0:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   6:	77 35                	ja     0x3d
   8:	44 89 c7             	mov    %r8d,%edi
   b:	89 44 24 0c          	mov    %eax,0xc(%rsp)
   f:	e8 21 79 04 00       	call   0x47935
  14:	8b                   	.byte 0x8b
  15:	44                   	rex.R
[   18.394198][  T231] RSP: 002b:00007ffe8ef08cd0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
[   18.394205][  T231] RAX: ffffffffffffffda RBX: 00007ffe8ef09230 RCX: 00000000004901eb
[   18.394208][  T231] RDX: 0000000000000002 RSI: 0000000000000002 RDI: 0000000000000005
[   18.394209][  T231] RBP: 00007ffe8ef08d10 R08: 0000000000000000 R09: 0000000000000000
[   18.394211][  T231] R10: 0000000039958030 R11: 0000000000000293 R12: 00007ffe8ef091a8
[   18.394213][  T231] R13: 0000000000000001 R14: 000000000054e030 R15: 0000000000000001
| [   18.404142][  T231] refcount_t: underflow; use-after-free.
| [   18.404383][  T231] WARNING: CPU: 2 PID: 231 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
| [   18.404750][  T231] Modules linked in:
| [   18.405267][  T231] Tainted: [B]=BAD_PAGE
[   18.405404][  T231] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   18.405625][  T231] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3))
[   18.405857][  T231] Code: 3f 92 02 80 fb 01 0f 87 bb b9 d9 fe 83 e3 01 0f 85 51 ff ff ff c6 05 5e 3f 92 02 01 90 48 c7 c7 20 8d e5 b6 e8 32 bf 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:	3f                   	(bad)
   1:	92                   	xchg   %eax,%edx
   2:	02 80 fb 01 0f 87    	add    -0x78f0fe05(%rax),%al
   8:	bb b9 d9 fe 83       	mov    $0x83fed9b9,%ebx
   d:	e3 01                	jrcxz  0x10
   f:	0f 85 51 ff ff ff    	jne    0xffffffffffffff66
  15:	c6 05 5e 3f 92 02 01 	movb   $0x1,0x2923f5e(%rip)        # 0x2923f7a
  1c:	90                   	nop
  1d:	48 c7 c7 20 8d e5 b6 	mov    $0xffffffffb6e58d20,%rdi
  24:	e8 32 bf 18 ff       	call   0xffffffffff18bf5b
  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
[   18.406428][  T231] RSP: 0018:ffffc90000787ce8 EFLAGS: 00010282
[   18.406650][  T231] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   18.406897][  T231] RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000001
[   18.407148][  T231] RBP: 0000000000000003 R08: 0000000000000000 R09: fffffbfff6efe134
[   18.407403][  T231] R10: 0000000000000003 R11: ffffc90000787880 R12: 0000000000000001
[   18.407662][  T231] R13: dffffc0000000000 R14: dead000000000122 R15: dead000000000100
[   18.407927][  T231] FS:  00000000399503c0(0000) GS:ffff88807d71a000(0000) knlGS:0000000000000000
[   18.408216][  T231] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   18.408431][  T231] CR2: 00007f20aa767000 CR3: 0000000009405002 CR4: 0000000000772ef0
[   18.408689][  T231] PKRU: 55555554
[   18.408835][  T231] Call Trace:
[   18.408972][  T231]  <TASK>
[   18.409073][  T231]  netdev_run_todo (./include/linux/list.h:381 net/core/dev.c:11670)
[   18.409251][  T231]  ? rtnl_is_locked (net/core/rtnetlink.c:169)
[   18.409425][  T231]  ? netif_state_change (./include/net/netdev_lock.h:72 ./include/net/netdev_lock.h:80 net/core/dev.c:1577)
[   18.409597][  T231]  ? call_netdevice_notifiers_info (net/core/dev.c:1576)
[   18.409816][  T231]  ? generic_xdp_install (net/core/dev.c:11630)
[   18.409992][  T231]  ? tun_chr_close (drivers/net/tun.c:638 drivers/net/tun.c:3436)
[   18.410170][  T231]  tun_chr_close (./include/net/sock.h:1990 drivers/net/tun.c:643 drivers/net/tun.c:3436)
[   18.410344][  T231]  __fput (fs/file_table.c:468)
[   18.410488][  T231]  fput_close_sync (fs/file_table.c:571)
[   18.410671][  T231]  ? alloc_file_clone (fs/file_table.c:571)
[   18.410847][  T231]  __x64_sys_close (fs/open.c:1592 fs/open.c:1574 fs/open.c:1574)
[   18.411022][  T231]  do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
[   18.411197][  T231]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[   18.411406][  T231] RIP: 0033:0x4901eb
[   18.411552][  T231] Code: 03 00 00 00 0f 05 48 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 c3 78 04 00 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 21 79 04 00 8b 44
All code
========
   0:	03 00                	add    (%rax),%eax
   2:	00 00                	add    %al,(%rax)
   4:	0f 05                	syscall
   6:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   c:	77 41                	ja     0x4f
   e:	c3                   	ret
   f:	48 83 ec 18          	sub    $0x18,%rsp
  13:	89 7c 24 0c          	mov    %edi,0xc(%rsp)
  17:	e8 c3 78 04 00       	call   0x478df
  1c:	8b 7c 24 0c          	mov    0xc(%rsp),%edi
  20:	41 89 c0             	mov    %eax,%r8d
  23:	b8 03 00 00 00       	mov    $0x3,%eax
  28:	0f 05                	syscall
  2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
  30:	77 35                	ja     0x67
  32:	44 89 c7             	mov    %r8d,%edi
  35:	89 44 24 0c          	mov    %eax,0xc(%rsp)
  39:	e8 21 79 04 00       	call   0x4795f
  3e:	8b                   	.byte 0x8b
  3f:	44                   	rex.R

Code starting with the faulting instruction
===========================================
   0:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   6:	77 35                	ja     0x3d
   8:	44 89 c7             	mov    %r8d,%edi
   b:	89 44 24 0c          	mov    %eax,0xc(%rsp)
   f:	e8 21 79 04 00       	call   0x47935
  14:	8b                   	.byte 0x8b
  15:	44                   	rex.R
[   18.412133][  T231] RSP: 002b:00007ffe8ef08cd0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
[   18.412386][  T231] RAX: ffffffffffffffda RBX: 00007ffe8ef09230 RCX: 00000000004901eb
[   18.412643][  T231] RDX: 0000000000000002 RSI: 0000000000000002 RDI: 0000000000000005
[   18.412895][  T231] RBP: 00007ffe8ef08d10 R08: 0000000000000000 R09: 0000000000000000
[   18.413142][  T231] R10: 0000000039958030 R11: 0000000000000293 R12: 00007ffe8ef091a8


Finger prints:
refcount_warn_saturate:netdev_run_todo:tun_chr_close:__fput:fput_close_sync
print_report:kasan_report:kobject_put:netdev_run_todo:tun_chr_close