======================================
| [ 1280.850551] ------------[ cut here ]------------
| [ 1280.850923] refcount_t: underflow; use-after-free.
| [ 1280.851329] WARNING: CPU: 1 PID: 69 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
| [ 1280.851992] Modules linked in: xt_HL amt xfrm_user l2tp_ip6 l2tp_eth l2tp_ip l2tp_netlink l2tp_core nft_compat nf_tables libcrc32c vxlan ip6_udp_tunnel udp_tunnel mpls_iptunnel mpls_router
[ 1280.853854] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 1280.854711] Workqueue: netns cleanup_net
[ 1280.855021] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[ 1280.855441] Code: 0b 90 90 c3 cc cc cc cc 80 3d 69 d4 67 01 00 0f 85 75 ff ff ff c6 05 5c d4 67 01 01 90 48 c7 c7 b8 37 13 b0 e8 a1 26 b4 ff 90 <0f> 0b 90 90 c3 cc cc cc cc 80 3d 3c d4 67 01 00 0f 85 4a ff ff ff
All code
========
   0:	0b 90 90 c3 cc cc    	or     -0x33333c70(%rax),%edx
   6:	cc                   	int3
   7:	cc                   	int3
   8:	80 3d 69 d4 67 01 00 	cmpb   $0x0,0x167d469(%rip)        # 0x167d478
   f:	0f 85 75 ff ff ff    	jne    0xffffffffffffff8a
  15:	c6 05 5c d4 67 01 01 	movb   $0x1,0x167d45c(%rip)        # 0x167d478
  1c:	90                   	nop
  1d:	48 c7 c7 b8 37 13 b0 	mov    $0xffffffffb01337b8,%rdi
  24:	e8 a1 26 b4 ff       	call   0xffffffffffb426ca
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	c3                   	ret
  2f:	cc                   	int3
  30:	cc                   	int3
  31:	cc                   	int3
  32:	cc                   	int3
  33:	80 3d 3c d4 67 01 00 	cmpb   $0x0,0x167d43c(%rip)        # 0x167d476
  3a:	0f 85 4a ff ff ff    	jne    0xffffffffffffff8a

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	c3                   	ret
   5:	cc                   	int3
   6:	cc                   	int3
   7:	cc                   	int3
   8:	cc                   	int3
   9:	80 3d 3c d4 67 01 00 	cmpb   $0x0,0x167d43c(%rip)        # 0x167d44c
  10:	0f 85 4a ff ff ff    	jne    0xffffffffffffff60
[ 1280.856840] RSP: 0018:ffffb5664026bd78 EFLAGS: 00010286
[ 1280.857255] RAX: 0000000000000000 RBX: ffff97be82b48000 RCX: 00000000ffffdfff
[ 1280.857804] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[ 1280.858338] RBP: ffff97be82b48610 R08: ffffffffb0578508 R09: 00000000ffffdfff
[ 1280.858771] R10: ffffffffb0498520 R11: ffffffffb0548520 R12: ffff97be82b48000
[ 1280.859166] R13: ffffb5664026be08 R14: ffff97be82b48b80 R15: ffff97be86f32e50
[ 1280.859580] FS:  0000000000000000(0000) GS:ffff97bebec80000(0000) knlGS:0000000000000000
[ 1280.860013] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1280.860331] CR2: 00007f668decc8e8 CR3: 000000000fc60003 CR4: 0000000000770ef0
[ 1280.860701] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1280.861086] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1280.861470] PKRU: 55555554
[ 1280.861614] Call Trace:
[ 1280.861748]  <TASK>
[ 1280.861891] ? __warn (kernel/panic.c:677) 
[ 1280.862074] ? refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[ 1280.862324] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[ 1280.862536] ? handle_bug (arch/x86/kernel/traps.c:238) 
[ 1280.862724] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[ 1280.862941] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[ 1280.863186] ? refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[ 1280.863434] ? refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[ 1280.863733] br_sysfs_delbr (net/bridge/br_sysfs_br.c:1086) 
[ 1280.863947] br_dev_delete (net/bridge/br_if.c:396) 
[ 1280.864164] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[ 1280.864400] cleanup_net (net/core/net_namespace.c:630) 
[ 1280.864593] ? process_one_work (kernel/workqueue.c:2606) 
[ 1280.864814] process_one_work (kernel/workqueue.c:2633) 
[ 1280.865049] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[ 1280.865267] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[ 1280.865512] kthread (kernel/kthread.c:388) 
[ 1280.865682] ? __pfx_kthread (kernel/kthread.c:341) 
[ 1280.865887] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 1280.866099] ? __pfx_kthread (kernel/kthread.c:341) 
[ 1280.866314] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [ 1280.869262] sysfs group 'bridge' not found for kobject 'br0'
| [ 1280.869569] WARNING: CPU: 1 PID: 69 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [ 1280.869994] Modules linked in: xt_HL amt xfrm_user l2tp_ip6 l2tp_eth l2tp_ip l2tp_netlink l2tp_core nft_compat nf_tables libcrc32c vxlan ip6_udp_tunnel udp_tunnel mpls_iptunnel mpls_router
|
[ 1280.871416] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
xx__-> [ 1280.872011] Workqueue: netns cleanup_net

[ 1280.872414] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 1280.872677] Code: 48 89 ef 5d 41 5c e9 7a ad ff ff 48 89 ef e8 12 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 a0 cd 12 b0 e8 ac 67 c5 ff 90 <0f> 0b 90 90 5b 5d 41 5c c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00
All code
========
   0:	48 89 ef             	mov    %rbp,%rdi
   3:	5d                   	pop    %rbp
   4:	41 5c                	pop    %r12
   6:	e9 7a ad ff ff       	jmp    0xffffffffffffad85
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 12 9b ff ff       	call   0xffffffffffff9b25
  13:	eb d1                	jmp    0xffffffffffffffe6
  15:	90                   	nop
  16:	49 8b 14 24          	mov    (%r12),%rdx
  1a:	48 8b 33             	mov    (%rbx),%rsi
  1d:	48 c7 c7 a0 cd 12 b0 	mov    $0xffffffffb012cda0,%rdi
  24:	e8 ac 67 c5 ff       	call   0xffffffffffc567d5
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	5b                   	pop    %rbx
  2f:	5d                   	pop    %rbp
  30:	41 5c                	pop    %r12
  32:	c3                   	ret
  33:	cc                   	int3
  34:	cc                   	int3
  35:	cc                   	int3
  36:	cc                   	int3
  37:	66                   	data16
  38:	66                   	data16
  39:	2e                   	cs
  3a:	0f                   	.byte 0xf
  3b:	1f                   	(bad)
  3c:	84 00                	test   %al,(%rax)
	...

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	5b                   	pop    %rbx
   5:	5d                   	pop    %rbp
   6:	41 5c                	pop    %r12
   8:	c3                   	ret
   9:	cc                   	int3
   a:	cc                   	int3
   b:	cc                   	int3
   c:	cc                   	int3
   d:	66                   	data16
   e:	66                   	data16
   f:	2e                   	cs
  10:	0f                   	.byte 0xf
  11:	1f                   	(bad)
  12:	84 00                	test   %al,(%rax)
	...
xx__-> [ 1280.873616] RSP: 0018:ffffb5664026bd70 EFLAGS: 00010286
[ 1280.873998] RAX: 0000000000000000 RBX: ffffffffafd472c0 RCX: 00000000ffffdfff
[ 1280.874370] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[ 1280.874741] RBP: 0000000000000000 R08: ffffffffb0578508 R09: 00000000ffffdfff
[ 1280.875116] R10: ffffffffb0498520 R11: ffffffffb0548520 R12: ffff97be82b48610
[ 1280.875482] R13: ffffb5664026be08 R14: ffff97be82b48b80 R15: ffff97be86f32e50
[ 1280.875853] FS:  0000000000000000(0000) GS:ffff97bebec80000(0000) knlGS:0000000000000000
[ 1280.876269] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1280.876570] CR2: 00007f668decc8e8 CR3: 000000000fc60003 CR4: 0000000000770ef0
[ 1280.876937] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1280.877313] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1280.877684] PKRU: 55555554
[ 1280.877828] Call Trace:
[ 1280.877960]  <TASK>
[ 1280.878092] ? __warn (kernel/panic.c:677) 
[ 1280.878275] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 1280.878505] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[ 1280.878706] ? handle_bug (arch/x86/kernel/traps.c:238) 
[ 1280.878914] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[ 1280.879135] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[ 1280.879378] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 1280.879618] br_dev_delete (net/bridge/br_if.c:396) 
[ 1280.879820] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[ 1280.880067] cleanup_net (net/core/net_namespace.c:630) 
[ 1280.880260] ? process_one_work (kernel/workqueue.c:2606) 
[ 1280.880502] process_one_work (kernel/workqueue.c:2633) 
[ 1280.880715] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[ 1280.880913] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[ 1280.881144] kthread (kernel/kthread.c:388) 
[ 1280.881312] ? __pfx_kthread (kernel/kthread.c:341) 
[ 1280.881511] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 1280.881716] ? __pfx_kthread (kernel/kthread.c:341) 


Finger prints:
refcount_warn_saturate:br_sysfs_delbr:br_dev_delete:br_net_exit_batch_rtnl
sysfs_remove_group:br_dev_delete:br_net_exit_batch_rtnl:cleanup_net