[v5.15] possible deadlock in rfkill_epo

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 12952a23a5da Linux 5.15.137
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=155eca63680000
kernel config: https://syzkaller.appspot.com/x/.config?x=d5d31a3160e35771
dashboard link: https://syzkaller.appspot.com/bug?extid=9b8d3d01564bddc23b05
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a52e721f848f/disk-12952a23.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f568d3b2b0c4/vmlinux-12952a23.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5c8641a162ac/Image-12952a23.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9b8d3d...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.15.137-syzkaller #0 Not tainted
------------------------------------------------------
kworker/0:8/9205 is trying to acquire lock:
ffff0000c12ccc28 ((work_completion)(&hdev->bg_scan_update)){+.+.}-{0:0}, at: __flush_work+0xd0/0x1c0 kernel/workqueue.c:3090

but task is already holding lock:
ffff800016c8cc08 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_epo+0x58/0x158 net/rfkill/core.c:450

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (rfkill_global_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
rfkill_register+0x44/0x7a4 net/rfkill/core.c:1045
hci_register_dev+0x3e0/0x880 net/bluetooth/hci_core.c:3959
__vhci_create_device drivers/bluetooth/hci_vhci.c:129 [inline]
vhci_create_device+0x2c4/0x568 drivers/bluetooth/hci_vhci.c:153
vhci_get_user drivers/bluetooth/hci_vhci.c:210 [inline]
vhci_write+0x318/0x3b8 drivers/bluetooth/hci_vhci.c:290
call_write_iter include/linux/fs.h:2103 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x87c/0xb3c fs/read_write.c:594
ksys_write+0x15c/0x26c fs/read_write.c:647
__do_sys_write fs/read_write.c:659 [inline]
__se_sys_write fs/read_write.c:656 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:656
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #3 (&data->open_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
vhci_send_frame+0x8c/0x10c drivers/bluetooth/hci_vhci.c:71
hci_send_frame+0x194/0x2f0 net/bluetooth/hci_core.c:4251
hci_sched_acl_pkt net/bluetooth/hci_core.c:4776 [inline]
hci_sched_acl net/bluetooth/hci_core.c:4861 [inline]
hci_tx_work+0x8d8/0x157c net/bluetooth/hci_core.c:4932
process_one_work+0x790/0x11b8 kernel/workqueue.c:2310
worker_thread+0x910/0x1034 kernel/workqueue.c:2457
kthread+0x37c/0x45c kernel/kthread.c:319
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

-> #2 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}:
__flush_work+0xf8/0x1c0 kernel/workqueue.c:3090
flush_work+0x24/0x38 kernel/workqueue.c:3115
hci_dev_do_close+0x16c/0x1060 net/bluetooth/hci_core.c:1756
hci_unregister_dev+0x228/0x4b4 net/bluetooth/hci_core.c:4035
vhci_release+0x74/0xc4 drivers/bluetooth/hci_vhci.c:345
__fput+0x30c/0x7f0 fs/file_table.c:280
____fput+0x20/0x30 fs/file_table.c:308
task_work_run+0x130/0x1e4 kernel/task_work.c:164
exit_task_work include/linux/task_work.h:32 [inline]
do_exit+0x688/0x2134 kernel/exit.c:872
do_group_exit+0x110/0x268 kernel/exit.c:994
get_signal+0x634/0x1550 kernel/signal.c:2889
do_signal arch/arm64/kernel/signal.c:890 [inline]
do_notify_resume+0x3d0/0x32b8 arch/arm64/kernel/signal.c:943
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
el0_svc+0xfc/0x1f0 arch/arm64/kernel/entry-common.c:609
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (&hdev->req_lock){+.+.}-{3:3}:
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
hci_req_sync net/bluetooth/hci_request.c:276 [inline]
bg_scan_update+0x9c/0x470 net/bluetooth/hci_request.c:2950
process_one_work+0x790/0x11b8 kernel/workqueue.c:2310
worker_thread+0x910/0x1034 kernel/workqueue.c:2457
kthread+0x37c/0x45c kernel/kthread.c:319
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

-> #0 ((work_completion)(&hdev->bg_scan_update)){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3787 [inline]
__lock_acquire+0x32cc/0x7620 kernel/locking/lockdep.c:5011
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__flush_work+0xf8/0x1c0 kernel/workqueue.c:3090
__cancel_work_timer+0x3ec/0x548 kernel/workqueue.c:3181
cancel_work_sync+0x24/0x38 kernel/workqueue.c:3217
hci_request_cancel_all+0xcc/0x2d0 net/bluetooth/hci_request.c:3520
hci_dev_do_close+0x54/0x1060 net/bluetooth/hci_core.c:1736
hci_rfkill_set_block+0xdc/0x1d0 net/bluetooth/hci_core.c:2235
rfkill_set_block+0x18c/0x37c net/rfkill/core.c:345
rfkill_epo+0x8c/0x158 net/rfkill/core.c:454
__rfkill_handle_global_op net/rfkill/input.c:60 [inline]
rfkill_op_handler+0x170/0x288 net/rfkill/input.c:108
process_one_work+0x790/0x11b8 kernel/workqueue.c:2310
worker_thread+0x910/0x1034 kernel/workqueue.c:2457
kthread+0x37c/0x45c kernel/kthread.c:319
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

other info that might help us debug this:

Chain exists of:
(work_completion)(&hdev->bg_scan_update) --> &data->open_mutex --> rfkill_global_mutex

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(rfkill_global_mutex);
lock(&data->open_mutex);
lock(rfkill_global_mutex);
lock((work_completion)(&hdev->bg_scan_update));

*** DEADLOCK ***

3 locks held by kworker/0:8/9205:
#0: ffff0000c0020d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x66c/0x11b8 kernel/workqueue.c:2283
#1: ffff800025617c00 ((rfkill_op_work).work){+.+.}-{0:0}, at: process_one_work+0x6ac/0x11b8 kernel/workqueue.c:2285
#2: ffff800016c8cc08 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_epo+0x58/0x158 net/rfkill/core.c:450

stack backtrace:
CPU: 0 PID: 9205 Comm: kworker/0:8 Not tainted 5.15.137-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: events rfkill_op_handler
Call trace:
dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3787 [inline]
__lock_acquire+0x32cc/0x7620 kernel/locking/lockdep.c:5011
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__flush_work+0xf8/0x1c0 kernel/workqueue.c:3090
__cancel_work_timer+0x3ec/0x548 kernel/workqueue.c:3181
cancel_work_sync+0x24/0x38 kernel/workqueue.c:3217
hci_request_cancel_all+0xcc/0x2d0 net/bluetooth/hci_request.c:3520
hci_dev_do_close+0x54/0x1060 net/bluetooth/hci_core.c:1736
hci_rfkill_set_block+0xdc/0x1d0 net/bluetooth/hci_core.c:2235
rfkill_set_block+0x18c/0x37c net/rfkill/core.c:345
rfkill_epo+0x8c/0x158 net/rfkill/core.c:454
__rfkill_handle_global_op net/rfkill/input.c:60 [inline]
rfkill_op_handler+0x170/0x288 net/rfkill/input.c:108
process_one_work+0x790/0x11b8 kernel/workqueue.c:2310
worker_thread+0x910/0x1034 kernel/workqueue.c:2457
kthread+0x37c/0x45c kernel/kthread.c:319
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 12952a23a5da Linux 5.15.137
git tree: linux-5.15.y

console output: https://syzkaller.appspot.com/x/log.txt?x=11ed13fd680000

kernel config: https://syzkaller.appspot.com/x/.config?x=d5d31a3160e35771
dashboard link: https://syzkaller.appspot.com/bug?extid=9b8d3d01564bddc23b05
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=132335fb680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1278e977680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a52e721f848f/disk-12952a23.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f568d3b2b0c4/vmlinux-12952a23.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5c8641a162ac/Image-12952a23.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9b8d3d...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.15.137-syzkaller #0 Not tainted
------------------------------------------------------

kworker/0:2/1713 is trying to acquire lock:
ffff0000c910cc28 ((work_completion)(&hdev->bg_scan_update)){+.+.}-{0:0}, at: __flush_work+0xd0/0x1c0 kernel/workqueue.c:3090

__do_sys_exit_group kernel/exit.c:1005 [inline]
__se_sys_exit_group kernel/exit.c:1003 [inline]
__wake_up_parent+0x0/0x60 kernel/exit.c:1003

__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

3 locks held by kworker/0:2/1713:

#0: ffff0000c0020d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x66c/0x11b8 kernel/workqueue.c:2283

#1: ffff8000214c7c00 ((rfkill_op_work).work){+.+.}-{0:0}, at: process_one_work+0x6ac/0x11b8 kernel/workqueue.c:2285

#2: ffff800016c8cc08 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_epo+0x58/0x158 net/rfkill/core.c:450

stack backtrace:

CPU: 0 PID: 1713 Comm: kworker/0:2 Not tainted 5.15.137-syzkaller #0

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.