[v5.15] possible deadlock in virtual_nci_close (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6e2fd6534337 Linux 5.15.213
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17f54bb9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f161cbc9aef65db0
dashboard link: https://syzkaller.appspot.com/bug?extid=f4d809da38ae4ce500d6
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d7b46606b13d/disk-6e2fd653.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/da120fdeb081/vmlinux-6e2fd653.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3c2643457e3f/bzImage-6e2fd653.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f4d809...@syzkaller.appspotmail.com

nci: __nci_request: wait_for_completion_interruptible_timeout failed -512
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.22/4347 is trying to acquire lock:
ffffffff8cb63968 (nci_mutex){+.+.}-{3:3}, at: virtual_nci_close+0x13/0x40 drivers/nfc/virtual_ncidev.c:44

but task is already holding lock:
ffff888061b76350 (&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:

-> #3 (&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_start_poll+0x8c8/0xcc0 net/nfc/nci/core.c:855
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

-> #2 (&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

-> #1 (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:3616 [inline]
path_openat+0x2718/0x2fb0 fs/namei.c:3750
do_filp_open+0x1df/0x400 fs/namei.c:3777
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

-> #0 (nci_mutex){+.+.}-{3:3}:
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:5623
__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_close+0x13/0x40 drivers/nfc/virtual_ncidev.c:44
nci_close_device+0x383/0x600 net/nfc/nci/core.c:591
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
get_signal+0x123e/0x12e0 kernel/signal.c:2681
arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
handle_signal_work kernel/entry/common.c:154 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
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:
nci_mutex --> &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(nci_mutex);

*** DEADLOCK ***

1 lock held by syz.4.22/4347:
#0: ffff888061b76350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_close_device+0x102/0x600 net/nfc/nci/core.c:560

stack backtrace:
CPU: 0 PID: 4347 Comm: syz.4.22 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:5623
__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_close+0x13/0x40 drivers/nfc/virtual_ncidev.c:44
nci_close_device+0x383/0x600 net/nfc/nci/core.c:591
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
get_signal+0x123e/0x12e0 kernel/signal.c:2681
arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
handle_signal_work kernel/entry/common.c:154 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f82cd7d5019
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:00007f82cba0c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: fffffffffffffff2 RBX: 00007f82cda5d090 RCX: 00007f82cd7d5019
RDX: 0000000000000102 RSI: 0000200000000840 RDI: 0000000000000003
RBP: 00007f82cd86c00c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f82cda5d128 R14: 00007f82cda5d090 R15: 00007ffe24530548
</TASK>


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