======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.1/4270 is trying to acquire lock:
ffff888077684138
 ((wq_completion)nfc2_nci_tx_wq
){+.+.}-{0:0}, at: flush_workqueue+0x14e/0x1390 kernel/workqueue.c:2830

but task is already holding lock:
ffff88802b31f350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_close_device+0x102/0x600 net/nfc/nci/core.c:560

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&ndev->req_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       nci_request net/nfc/nci/core.c:148 [inline]
       nci_set_local_general_bytes net/nfc/nci/core.c:776 [inline]
       nci_start_poll+0x529/0xcc0 net/nfc/nci/core.c:840
       nfc_start_poll+0x141/0x2c0 net/nfc/core.c:225
       nfc_genl_start_poll+0x1d7/0x340 net/nfc/netlink.c:828
       genl_family_rcv_msg_doit net/netlink/genetlink.c:731 [inline]
       genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
       genl_rcv_msg+0xd0b/0xfa0 net/netlink/genetlink.c:792
       netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2519
       genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
       netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
       netlink_unicast+0x78f/0x940 net/netlink/af_netlink.c:1340
       netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1919
       sock_sendmsg_nosec net/socket.c:706 [inline]
       __sock_sendmsg net/socket.c:718 [inline]
       ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2446
       ___sys_sendmsg+0x236/0x2e0 net/socket.c:2500
       __sys_sendmsg net/socket.c:2529 [inline]
       __do_sys_sendmsg net/socket.c:2538 [inline]
       __se_sys_sendmsg+0x1b7/0x2a0 net/socket.c:2536
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #4 (&genl_data->genl_data_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       nfc_urelease_event_work+0x120/0x310 net/nfc/netlink.c:1833
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #3 (nfc_devlist_mutex
){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       nfc_register_device+0x38/0x300 net/nfc/core.c:1116
       nci_register_device+0x89f/0x9f0 net/nfc/nci/core.c:1276
       virtual_ncidev_open+0x55/0xc0 drivers/nfc/virtual_ncidev.c:146
       misc_open+0x31f/0x390 drivers/char/misc.c:143
       chrdev_open+0x585/0x5f0 fs/char_dev.c:414
       do_dentry_open+0x7f7/0xf90 fs/open.c:826
       do_open fs/namei.c:3659 [inline]
       path_openat+0x2718/0x2fb0 fs/namei.c:3793
       do_filp_open+0x1df/0x400 fs/namei.c:3820
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (nci_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       virtual_nci_send+0x1d/0xd0 drivers/nfc/virtual_ncidev.c:54
       nci_tx_work+0x19f/0x3a0 net/nfc/nci/core.c:1531
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #1 ((work_completion)(&ndev->tx_work)){+.+.}-{0:0}:
       process_one_work+0x7ba/0xff0 kernel/workqueue.c:2286
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #0 ((wq_completion)nfc2_nci_tx_wq){+.+.}-{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:3788 [inline]
       __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625
       flush_workqueue+0x16a/0x1390 kernel/workqueue.c:2830
       nci_close_device+0x172/0x600 net/nfc/nci/core.c:578
       nci_unregister_device+0x5e/0x250 net/nfc/nci/core.c:1313
       virtual_ncidev_close+0x55/0x90 drivers/nfc/virtual_ncidev.c:166
       __fput+0x212/0x8c0 fs/file_table.c:311
       task_work_run+0x125/0x1a0 kernel/task_work.c:188
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:184
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
       __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
       syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
       do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  (wq_completion)nfc2_nci_tx_wq --> &genl_data->genl_data_mutex --> &ndev->req_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ndev->req_lock);
                               lock(&genl_data->genl_data_mutex);
                               lock(&ndev->req_lock);
  lock((wq_completion)nfc2_nci_tx_wq);

 *** DEADLOCK ***

1 lock held by syz.0.1/4270:
 #0: ffff88802b31f350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_close_device+0x102/0x600 net/nfc/nci/core.c:560

stack backtrace:
CPU: 1 PID: 4270 Comm: syz.0.1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 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:3788 [inline]
 __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625
 flush_workqueue+0x16a/0x1390 kernel/workqueue.c:2830
 nci_close_device+0x172/0x600 net/nfc/nci/core.c:578
 nci_unregister_device+0x5e/0x250 net/nfc/nci/core.c:1313
 virtual_ncidev_close+0x55/0x90 drivers/nfc/virtual_ncidev.c:166
 __fput+0x212/0x8c0 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:184
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
 __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f20c2feb159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe37beef48 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f20c3274da0 RCX: 00007f20c2feb159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f20c3274da0 R08: 00007f20c3273038 R09: 0000000000000000
R10: 00000000003ffb20 R11: 0000000000000246 R12: 000000000001055a
R13: 00007f20c3272fac R14: 00000000000102ca R15: 00007ffe37bef050
 </TASK>
nci: __nci_request: wait_for_completion_interruptible_timeout failed -512
------------[ cut here ]------------
ODEBUG: free active (active state 0) object type: timer_list hint: arch_atomic_set arch/x86/include/asm/atomic.h:-1 [inline]
ODEBUG: free active (active state 0) object type: timer_list hint: atomic_set include/linux/atomic/atomic-instrumented.h:42 [inline]
ODEBUG: free active (active state 0) object type: timer_list hint: nci_data_timer+0x0/0x60 net/nfc/nci/core.c:616
WARNING: CPU: 0 PID: 4270 at lib/debugobjects.c:521 debug_print_object lib/debugobjects.c:518 [inline]
WARNING: CPU: 0 PID: 4270 at lib/debugobjects.c:521 __debug_check_no_obj_freed lib/debugobjects.c:990 [inline]
WARNING: CPU: 0 PID: 4270 at lib/debugobjects.c:521 debug_check_no_obj_freed+0x395/0x520 lib/debugobjects.c:1020
Modules linked in:
CPU: 1 PID: 4270 Comm: syz.0.1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:debug_print_object lib/debugobjects.c:518 [inline]
RIP: 0010:__debug_check_no_obj_freed lib/debugobjects.c:990 [inline]
RIP: 0010:debug_check_no_obj_freed+0x395/0x520 lib/debugobjects.c:1020
Code: e8 60 ea d0 fd 4c 8b 45 00 48 c7 c7 e0 51 7a 8a 48 c7 c6 a0 4e 7a 8a 48 c7 c2 40 53 7a 8a 8b 4c 24 1c 4d 89 e9 e8 ab eb c8 05 <0f> 0b 4c 8b 6c 24 10 48 b9 00 00 00 00 00 fc ff df ff 05 6c f4 9d
RSP: 0018:ffffc9000315fcc8 EFLAGS: 00010246
RAX: e180e93bff60aa00 RBX: ffffffff96581718 RCX: ffff888021518000
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffffff8a2cacc0 R08: ffff8880b9033d7f R09: 1ffff110172067af
R10: dffffc0000000000 R11: ffffed10172067b0 R12: 0000000000000001
R13: ffffffff899c12d0 R14: ffff88802b31f000 R15: ffff88802b31f0a0
FS:  0000555589f8c500(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe2dd9a928 CR3: 000000001f2e1000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 slab_free_hook mm/slub.c:1685 [inline]
 slab_free_freelist_hook+0x8b/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 virtual_ncidev_close+0x61/0x90 drivers/nfc/virtual_ncidev.c:167
 __fput+0x212/0x8c0 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:184
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
 __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f20c2feb159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe37beef48 EFLAGS: 00000246
 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f20c3274da0 RCX: 00007f20c2feb159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f20c3274da0 R08: 00007f20c3273038 R09: 0000000000000000
R10: 00000000003ffb20 R11: 0000000000000246 R12: 000000000001055a
R13: 00007f20c3272fac R14: 00000000000102ca R15: 00007ffe37bef050
 </TASK>