====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.295/5329 is trying to acquire lock: ffff8880287c2350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_request net/nfc/nci/core.c:148 [inline] ffff8880287c2350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_set_local_general_bytes net/nfc/nci/core.c:776 [inline] ffff8880287c2350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_start_poll+0x529/0xcc0 net/nfc/nci/core.c:840 but task is already holding lock: ffff888067cf7510 (&genl_data->genl_data_mutex){+.+.}-{3:3}, at: nfc_genl_start_poll+0x1c9/0x340 net/nfc/netlink.c:826 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&genl_data->genl_data_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 nfc_urelease_event_work+0x120/0x310 net/nfc/netlink.c:1849 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 -> #2 (nfc_devlist_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 nfc_register_device+0x38/0x300 net/nfc/core.c:1116 nci_register_device+0x89f/0x9f0 net/nfc/nci/core.c:1272 virtual_ncidev_open+0x55/0xc0 drivers/nfc/virtual_ncidev.c:146 misc_open+0x31f/0x390 drivers/char/misc.c:145 chrdev_open+0x585/0x5f0 fs/char_dev.c:414 do_dentry_open+0x7dd/0x10b0 fs/open.c:882 do_open fs/namei.c:3677 [inline] path_openat+0x2674/0x2f10 fs/namei.c:3834 do_filp_open+0x1ee/0x420 fs/namei.c:3861 do_sys_openat2+0x14b/0x4f0 fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __x64_sys_openat+0x135/0x160 fs/open.c:1347 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #1 (nci_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 virtual_nci_close+0x13/0x40 drivers/nfc/virtual_ncidev.c:44 nci_open_device net/nfc/nci/core.c:544 [inline] nci_dev_up+0x976/0xd90 net/nfc/nci/core.c:633 nfc_dev_up+0x15d/0x310 net/nfc/core.c:118 nfc_genl_dev_up+0x85/0xd0 net/nfc/netlink.c:770 genl_family_rcv_msg_doit+0x22f/0x350 net/netlink/genetlink.c:756 genl_family_rcv_msg net/netlink/genetlink.c:833 [inline] genl_rcv_msg+0x601/0x790 net/netlink/genetlink.c:850 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516 genl_rcv+0x24/0x40 net/netlink/genetlink.c:861 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573 __sys_sendmsg net/socket.c:2602 [inline] __do_sys_sendmsg net/socket.c:2611 [inline] __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (&ndev->req_lock){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5678 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 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+0x22f/0x350 net/netlink/genetlink.c:756 genl_family_rcv_msg net/netlink/genetlink.c:833 [inline] genl_rcv_msg+0x601/0x790 net/netlink/genetlink.c:850 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516 genl_rcv+0x24/0x40 net/netlink/genetlink.c:861 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573 __sys_sendmsg net/socket.c:2602 [inline] __do_sys_sendmsg net/socket.c:2611 [inline] __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Chain exists of: &ndev->req_lock --> nfc_devlist_mutex --> &genl_data->genl_data_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&genl_data->genl_data_mutex); lock(nfc_devlist_mutex); lock(&genl_data->genl_data_mutex); lock(&ndev->req_lock); *** DEADLOCK *** 4 locks held by syz.2.295/5329: #0: ffffffff8ddb5b90 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:860 #1: ffffffff8ddb59a8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline] #1: ffffffff8ddb59a8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x107/0x790 net/netlink/genetlink.c:848 #2: ffff888067cf7510 (&genl_data->genl_data_mutex){+.+.}-{3:3}, at: nfc_genl_start_poll+0x1c9/0x340 net/nfc/netlink.c:826 #3: ffff888067cf7100 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline] #3: ffff888067cf7100 (&dev->mutex){....}-{3:3}, at: nfc_start_poll+0x4f/0x2c0 net/nfc/core.c:208 stack backtrace: CPU: 1 PID: 5329 Comm: syz.2.295 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5678 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 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+0x22f/0x350 net/netlink/genetlink.c:756 genl_family_rcv_msg net/netlink/genetlink.c:833 [inline] genl_rcv_msg+0x601/0x790 net/netlink/genetlink.c:850 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516 genl_rcv+0x24/0x40 net/netlink/genetlink.c:861 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573 __sys_sendmsg net/socket.c:2602 [inline] __do_sys_sendmsg net/socket.c:2611 [inline] __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fe9b119e159 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:00007fe9b1fad028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fe9b1426090 RCX: 00007fe9b119e159 RDX: 0000000000000800 RSI: 00002000000005c0 RDI: 0000000000000005 RBP: 00007fe9b123506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe9b1426128 R14: 00007fe9b1426090 R15: 00007ffefdb03d48 nci: __nci_request: wait_for_completion_interruptible_timeout failed -512 nci: nci_start_poll: failed to set local general bytes