WARNING in kernfs

WARNING in kernfs_get
Status: upstream: reported C repro on 2019/04/26 00:08
Reported-by: syzbot+4950f058cfd2f22b7a83@syzkaller.appspotmail.com
First crash: 179d, last: 39d

similar bugs (3):
Kernel	Title	Repro	Count	Last	Reported	Patched	Status
linux-4.14	WARNING in kernfs_get	C	17	63d	183d	0/1	upstream: reported C repro on 2019/04/21 18:18
upstream	WARNING in kernfs_get	C	316	78d	406d	0/14	upstream: reported C repro on 2018/09/10 07:31
android-414	WARNING in kernfs_get	syz	69	42d	194d	0/1	public: reported syz repro on 2019/04/10 15:44

Sample crash report:

WARNING: CPU: 1 PID: 8545 at fs/kernfs/dir.c:494 kernfs_get.part.0+0x73/0x90 fs/kernfs/dir.c:494
Kernel panic - not syncing: panic_on_warn set ...

kobject: 'bluetooth' (000000007057208c): kobject_add_internal: parent: 'virtual', set: '(null)'
CPU: 1 PID: 8545 Comm: syz-executor751 Not tainted 4.19.36 #4
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+0x172/0x1f0 lib/dump_stack.c:113
 panic+0x263/0x51d kernel/panic.c:185
kobject: 'hci2' (00000000f1206a10): kobject_add_internal: parent: 'bluetooth', set: 'devices'
 __warn.cold+0x20/0x54 kernel/panic.c:540
 report_bug+0x263/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 fixup_bug arch/x86/kernel/traps.c:173 [inline]
 do_error_trap+0x204/0x360 arch/x86/kernel/traps.c:296
kobject: 'hci2' (00000000f1206a10): kobject_uevent_env
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
kobject: 'hci2' (00000000f1206a10): fill_kobj_path: path = '/devices/virtual/bluetooth/hci2'
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:997
RIP: 0010:kernfs_get.part.0+0x73/0x90 fs/kernfs/dir.c:494
Code: e6 e8 01 8a 9e ff 45 85 e4 74 1a e8 77 88 9e ff be 04 00 00 00 48 89 df e8 4a d9 d4 ff f0 ff 03 5b 41 5c 5d c3 e8 5d 88 9e ff <0f> 0b eb dd 48 89 df e8 a1 e9 d4 ff eb c1 0f 1f 44 00 00 66 2e 0f
RSP: 0018:ffff88808fe17840 EFLAGS: 00010293
kobject: 'rfkill746' (00000000d78dec35): kobject_add_internal: parent: 'hci2', set: 'devices'
RAX: ffff88807dfa2280 RBX: ffff8880a01b6d20 RCX: ffffffff81ccbc8f
RDX: 0000000000000000 RSI: ffffffff81ccbcb3 RDI: 0000000000000005
RBP: ffff88808fe17850 R08: ffff88807dfa2280 R09: ffffed1014036da5
R10: ffffed1014036da4 R11: ffff8880a01b6d23 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
 kernfs_get fs/kernfs/dir.c:493 [inline]
 kernfs_new_node+0xb8/0x130 fs/kernfs/dir.c:698
kobject: 'rfkill746' (00000000d78dec35): kobject_uevent_env
 kernfs_create_dir_ns+0x52/0x160 fs/kernfs/dir.c:1021
 sysfs_create_dir_ns+0x131/0x290 fs/sysfs/dir.c:58
 create_dir lib/kobject.c:88 [inline]
 kobject_add_internal lib/kobject.c:247 [inline]
 kobject_add_internal.cold+0xe5/0x5d4 lib/kobject.c:217
 kobject_add_varg lib/kobject.c:382 [inline]
 kobject_add+0x150/0x1c0 lib/kobject.c:426
kobject: 'rfkill746' (00000000d78dec35): fill_kobj_path: path = '/devices/virtual/bluetooth/hci2/rfkill746'
kobject: 'rfkill746' (00000000d78dec35): kobject_uevent_env
 device_add+0x3cc/0x1770 drivers/base/core.c:1885
kobject: 'rfkill746' (00000000d78dec35): fill_kobj_path: path = '/devices/virtual/bluetooth/hci2/rfkill746'
 hci_register_dev+0x304/0x880 net/bluetooth/hci_core.c:3198
 __vhci_create_device+0x2d0/0x5a0 drivers/bluetooth/hci_vhci.c:139
 vhci_create_device drivers/bluetooth/hci_vhci.c:163 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:219 [inline]
 vhci_write+0x2d6/0x470 drivers/bluetooth/hci_vhci.c:299
kobject: 'rfkill746' (00000000d78dec35): kobject_cleanup, parent           (null)
 call_write_iter include/linux/fs.h:1811 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x58e/0x820 fs/read_write.c:487
kobject: 'rfkill746' (00000000d78dec35): calling ktype release
 vfs_write+0x20c/0x560 fs/read_write.c:549
 ksys_write+0xea/0x1f0 fs/read_write.c:598
kobject: 'rfkill746': free name
 __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+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441269
kobject: 'hci2' (00000000f1206a10): kobject_uevent_env
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 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe2035a008 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441269
RDX: 0000000000000002 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 000000000000dc25 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000401fe0
R13: 0000000000402070 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (14):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci2-linux-4-19	2019/04/25 23:08	linux-4.19.y	c98875d9	f46aabc8	.config	log	report	syz	C	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/09/12 16:08	linux-4.19.y	ee809c7e	0b7672ee	.config	log	report	syz	C	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/08/01 20:46	linux-4.19.y	9a9de33a	835dffe7	.config	log	report	syz	C	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/07/16 22:04	linux-4.19.y	3bd837bf	4ec4ea48	.config	log	report	syz	C	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/06/30 05:58	linux-4.19.y	aec3002d	7509bf36	.config	log	report	syz	C	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/06/07 18:04	linux-4.19.y	e109a984	cf9c3a50	.config	log	report	syz	C	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/08/31 20:55	linux-4.19.y	97ab07e1	bad3cce2	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/08/15 18:55	linux-4.19.y	893af1c7	faeffb00	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/07/23 22:10	linux-4.19.y	be9b6782	de453f34	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/07/21 01:08	linux-4.19.y	3bd837bf	1656845f	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/06/27 15:50	linux-4.19.y	aec3002d	7509bf36	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/06/27 03:34	linux-4.19.y	aec3002d	7509bf36	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/06/12 15:17	linux-4.19.y	768292d0	794a1ad7	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org
ci2-linux-4-19	2019/06/04 19:22	linux-4.19.y	e109a984	e41a20c5	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tj@kernel.org