Subject: [syzbot] possible deadlock in virtual_nci_close

From: syzbot <[email-masked]>
Date: Sun, 13 Nov 2022 19:11:51 -0800

Hello,

syzbot found the following issue on:

HEAD commit:    af7a05689189 Merge tag 'mips-fixes_6.1_1' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13d30249880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9d1d2dd6d424a076
dashboard link: https://syzkaller.appspot.com/bug?extid=8040d16d30c215f821de
compiler:       aarch64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

nci: __nci_request: wait_for_completion_interruptible_timeout failed 0
======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc4-syzkaller-00372-gaf7a05689189 #0 Not tainted
------------------------------------------------------
syz-executor.1/8551 is trying to acquire lock:
ffff80000e6854c8 (nci_mutex){+.+.}-{3:3}, at: virtual_nci_close+0x2c/0x60 drivers/nfc/virtual_ncidev.c:44

but task is already holding lock:
ffff000030115350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_close_device+0x5c/0x360 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 kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x124/0x83c kernel/locking/mutex.c:747
       mutex_lock_nested+0x2c/0x40 kernel/locking/mutex.c:799
       nci_request net/nfc/nci/core.c:148 [inline]
       nci_set_local_general_bytes net/nfc/nci/core.c:774 [inline]
       nci_start_poll+0x36c/0x624 net/nfc/nci/core.c:838
       nfc_start_poll+0x114/0x270 net/nfc/core.c:225
       nfc_genl_start_poll+0x154/0x3b0 net/nfc/netlink.c:828
       genl_family_rcv_msg_doit+0x1b8/0x2a0 net/netlink/genetlink.c:756
       genl_family_rcv_msg net/netlink/genetlink.c:833 [inline]
       genl_rcv_msg+0x2f8/0x594 net/netlink/genetlink.c:850
       netlink_rcv_skb+0x180/0x330 net/netlink/af_netlink.c:2540
       genl_rcv+0x38/0x50 net/netlink/genetlink.c:861
       netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
       netlink_unicast+0x3ec/0x684 net/netlink/af_netlink.c:1345
       netlink_sendmsg+0x690/0xb1c net/netlink/af_netlink.c:1921
       sock_sendmsg_nosec net/socket.c:714 [inline]
       sock_sendmsg+0xc0/0xf4 net/socket.c:734
       ____sys_sendmsg+0x534/0x6b0 net/socket.c:2482
       ___sys_sendmsg+0xf0/0x174 net/socket.c:2536
       __sys_sendmsg+0xc4/0x154 net/socket.c:2565
       __do_sys_sendmsg net/socket.c:2574 [inline]
       __se_sys_sendmsg net/socket.c:2572 [inline]
       __arm64_sys_sendmsg+0x70/0xa0 net/socket.c:2572
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52
       el0_svc_common.constprop.0+0xc4/0x254 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x50/0x14c arch/arm64/kernel/syscall.c:206
       el0_svc+0x54/0x140 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0xb8/0xc0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

-> #2 (&genl_data->genl_data_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x124/0x83c kernel/locking/mutex.c:747
       mutex_lock_nested+0x2c/0x40 kernel/locking/mutex.c:799
       nfc_urelease_event_work+0x118/0x270 net/nfc/netlink.c:1811
       process_one_work+0x780/0x184c kernel/workqueue.c:2289
       worker_thread+0x3cc/0xc40 kernel/workqueue.c:2436
       kthread+0x23c/0x2a0 kernel/kthread.c:376
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

-> #1 (nfc_devlist_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x124/0x83c kernel/locking/mutex.c:747
       mutex_lock_nested+0x2c/0x40 kernel/locking/mutex.c:799
       nfc_register_device+0x34/0x320 net/nfc/core.c:1116
       nci_register_device+0x604/0x8c0 net/nfc/nci/core.c:1256
       virtual_ncidev_open+0x64/0xe0 drivers/nfc/virtual_ncidev.c:146
       misc_open+0x294/0x394 drivers/char/misc.c:143
       chrdev_open+0x1c0/0x54c fs/char_dev.c:414
       do_dentry_open+0x3c4/0xf40 fs/open.c:882
       vfs_open+0x90/0xd0 fs/open.c:1013
       do_open fs/namei.c:3557 [inline]
       path_openat+0x1030/0x1fe0 fs/namei.c:3713
       do_filp_open+0x154/0x330 fs/namei.c:3740
       do_sys_openat2+0x124/0x390 fs/open.c:1310
       do_sys_open fs/open.c:1326 [inline]
       __do_sys_openat fs/open.c:1342 [inline]
       __se_sys_openat fs/open.c:1337 [inline]
       __arm64_sys_openat+0x130/0x1c0 fs/open.c:1337
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52
       el0_svc_common.constprop.0+0xc4/0x254 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x50/0x14c arch/arm64/kernel/syscall.c:206
       el0_svc+0x54/0x140 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0xb8/0xc0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

-> #0 (nci_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3097 [inline]
       check_prevs_add kernel/locking/lockdep.c:3216 [inline]
       validate_chain kernel/locking/lockdep.c:3831 [inline]
       __lock_acquire+0x2788/0x56d0 kernel/locking/lockdep.c:5055
       lock_acquire kernel/locking/lockdep.c:5668 [inline]
       lock_acquire+0x58c/0x9a0 kernel/locking/lockdep.c:5633
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x124/0x83c kernel/locking/mutex.c:747
       mutex_lock_nested+0x2c/0x40 kernel/locking/mutex.c:799
       virtual_nci_close+0x2c/0x60 drivers/nfc/virtual_ncidev.c:44
       nci_close_device+0x200/0x360 net/nfc/nci/core.c:592
       nci_unregister_device+0x40/0x280 net/nfc/nci/core.c:1291
       virtual_ncidev_close+0x70/0x90 drivers/nfc/virtual_ncidev.c:166
       __fput+0x1ac/0x860 fs/file_table.c:320
       ____fput+0x10/0x1c fs/file_table.c:348
       task_work_run+0x12c/0x220 kernel/task_work.c:179
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       do_notify_resume+0x920/0x2840 arch/arm64/kernel/signal.c:1127
       prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
       exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
       el0_svc+0x11c/0x140 arch/arm64/kernel/entry-common.c:638
       el0t_64_sync_handler+0xb8/0xc0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

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-executor.1/8551:
 #0: ffff000030115350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_close_device+0x5c/0x360 net/nfc/nci/core.c:560

stack backtrace:
CPU: 1 PID: 8551 Comm: syz-executor.1 Not tainted 6.1.0-rc4-syzkaller-00372-gaf7a05689189 #0
Hardware name: linux,dummy-virt (DT)
Call trace:
 dump_backtrace+0xe0/0x140 arch/arm64/kernel/stacktrace.c:156
 show_stack+0x18/0x40 arch/arm64/kernel/stacktrace.c:163
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x9c/0xd8 lib/dump_stack.c:106
 dump_stack+0x1c/0x38 lib/dump_stack.c:113
 print_circular_bug+0x2d4/0x2ec kernel/locking/lockdep.c:2055
 check_noncircular+0x26c/0x2e0 kernel/locking/lockdep.c:2177
 check_prev_add kernel/locking/lockdep.c:3097 [inline]
 check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 validate_chain kernel/locking/lockdep.c:3831 [inline]
 __lock_acquire+0x2788/0x56d0 kernel/locking/lockdep.c:5055
 lock_acquire kernel/locking/lockdep.c:5668 [inline]
 lock_acquire+0x58c/0x9a0 kernel/locking/lockdep.c:5633
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x124/0x83c kernel/locking/mutex.c:747
 mutex_lock_nested+0x2c/0x40 kernel/locking/mutex.c:799
 virtual_nci_close+0x2c/0x60 drivers/nfc/virtual_ncidev.c:44
 nci_close_device+0x200/0x360 net/nfc/nci/core.c:592
 nci_unregister_device+0x40/0x280 net/nfc/nci/core.c:1291
 virtual_ncidev_close+0x70/0x90 drivers/nfc/virtual_ncidev.c:166
 __fput+0x1ac/0x860 fs/file_table.c:320
 ____fput+0x10/0x1c fs/file_table.c:348
 task_work_run+0x12c/0x220 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 do_notify_resume+0x920/0x2840 arch/arm64/kernel/signal.c:1127
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_svc+0x11c/0x140 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0xb8/0xc0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

---
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