Re: WARNING in sysfs_remove_group (2)

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit:    e195ca6cb6f2 Merge branch 'for-linus' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1659a62b400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=73e2bc0cb6463446
dashboard link: https://syzkaller.appspot.com/bug?extid=34cbd0f790e5ab87f63b
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14dad1f5400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1211db83400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+34cbd0f790e5ab87f63b@xxxxxxxxxxxxxxxxxxxxxxxxx

kobject_add_internal failed for hci3 (error: -2 parent: bluetooth)
------------[ cut here ]------------
Bluetooth: Can't register HCI device
sysfs group 'power' not found for kobject 'hci0'
WARNING: CPU: 1 PID: 6615 at fs/sysfs/group.c:255  
sysfs_remove_group+0x15b/0x1b0 fs/sysfs/group.c:253
kobject: 'bluetooth' (0000000099b926db): kobject_add_internal:  
parent: 'virtual', set: '(null)'
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 6615 Comm: syz-executor148 Not tainted 4.20.0-rc3+ #128
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x244/0x39d lib/dump_stack.c:113
 panic+0x2ad/0x55c kernel/panic.c:188
kobject: 'hci4' (00000000b7b152ea): kobject_add_internal:  
parent: 'bluetooth', set: 'devices'
 __warn.cold.8+0x20/0x45 kernel/panic.c:540
kobject: 'hci3' (00000000de75fad9): kobject_add_internal:  
parent: 'bluetooth', set: 'devices'
 report_bug+0x254/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
kobject: 'hci4' (00000000b7b152ea): kobject_uevent_env
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969
RIP: 0010:sysfs_remove_group+0x15b/0x1b0 fs/sysfs/group.c:253
kobject: 'hci1' (000000005f181f76): kobject_add_internal:  
parent: 'bluetooth', set: 'devices'
Code: 48 89 d9 49 8b 55 00 48 b8 00 00 00 00 00 fc ff df 48 c1 e9 03 80 3c  
01 00 75 41 48 8b 33 48 c7 c7 a0 bb 37 88 e8 85 2e 4f ff <0f> 0b eb 92 e8  
3c 1d c9 ff e9 d0 fe ff ff 48 89 df e8 2f 1d c9 ff
RSP: 0018:ffff8881b01878b8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffffffff887c3640 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8165eaf5 RDI: 0000000000000005
RBP: ffff8881b01878e0 R08: ffff8881abd72700 R09: ffffed103b5e3ef8
R10: ffffed103b5e3ef8 R11: ffff8881daf1f7c7 R12: 0000000000000000
R13: ffff8881abf02890 R14: ffffffff887c3be0 R15: ffff8881abf02880
 dpm_sysfs_add+0x1cf/0x210 drivers/base/power/sysfs.c:678
 device_add+0x8d8/0x18e0 drivers/base/core.c:1902
kobject: 'hci4' (00000000b7b152ea): fill_kobj_path: path  
= '/devices/virtual/bluetooth/hci4'
kobject: 'hci5' (0000000072db0368): kobject_add_internal:  
parent: 'bluetooth', set: 'devices'
kobject: 'hci3' (00000000de75fad9): kobject_uevent_env
 hci_register_dev+0x3b3/0x9c0 net/bluetooth/hci_core.c:3261
kobject: 'hci1' (000000005f181f76): kobject_uevent_env
 __vhci_create_device+0x2c1/0x580 drivers/bluetooth/hci_vhci.c:139
kobject: 'hci5' (0000000072db0368): kobject_uevent_env
 vhci_create_device drivers/bluetooth/hci_vhci.c:163 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:219 [inline]
 vhci_write+0x2de/0x470 drivers/bluetooth/hci_vhci.c:299
kobject: 'hci1' (000000005f181f76): fill_kobj_path: path  
= '/devices/virtual/bluetooth/hci1'
 call_write_iter include/linux/fs.h:1857 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x6b8/0x9f0 fs/read_write.c:487
kobject: 'hci2' (000000008e0439e5): kobject_add_internal:  
parent: 'bluetooth', set: 'devices'
 vfs_write+0x1fc/0x560 fs/read_write.c:549
 ksys_write+0x101/0x260 fs/read_write.c:598
kobject: 'hci3' (00000000de75fad9): fill_kobj_path: path  
= '/devices/virtual/bluetooth/hci3'
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write fs/read_write.c:607 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:607
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
kobject: 'rfkill466' (000000008955fb87): kobject_add_internal:  
parent: 'hci4', set: 'devices'
kobject: 'hci5' (0000000072db0368): fill_kobj_path: path  
= '/devices/virtual/bluetooth/hci5'
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440e49
Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 0b 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00
kobject: 'rfkill466' (000000008955fb87): kobject_uevent_env
RSP: 002b:00007ffd93629a18 EFLAGS: 00000213 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440e49
RDX: 0000000000000002 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000ddb880 R11: 0000000000000213 R12: 000000000000ee45
kobject: 'hci2' (000000008e0439e5): kobject_uevent_env
R13: 0000000000401d70 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..