syzbot


possible deadlock in hci_dev_close

Status: upstream: reported on 2024/04/30 22:51
Subsystems: bluetooth
[Documentation on labels]
Reported-by: syzbot+27678574afc8747c97f3@syzkaller.appspotmail.com
First crash: 49d, last: 45d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bluetooth?] possible deadlock in hci_dev_close 0 (1) 2024/04/30 22:51

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc6-next-20240430-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/5889 is trying to acquire lock:
ffff88802c7c08d0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
ffff88802c7c08d0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
ffff88802c7c08d0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4122 [inline]
ffff88802c7c08d0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: __flush_work+0xe6/0xd00 kernel/workqueue.c:4181

but task is already holding lock:
ffff88802c7c1060 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:559 [inline]
ffff88802c7c1060 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_close+0x10a/0x210 net/bluetooth/hci_core.c:586

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&hdev->req_lock){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       hci_cmd_sync_work+0x1ec/0x400 net/bluetooth/hci_sync.c:309
       process_one_work kernel/workqueue.c:3231 [inline]
       process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
       worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
       kthread+0x2f0/0x390 kernel/kthread.c:389
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       touch_work_lockdep_map kernel/workqueue.c:3894 [inline]
       start_flush_work kernel/workqueue.c:4148 [inline]
       __flush_work+0x73c/0xd00 kernel/workqueue.c:4181
       __cancel_work_sync+0xbc/0x110 kernel/workqueue.c:4331
       hci_cmd_sync_clear+0x30/0x220 net/bluetooth/hci_sync.c:588
       hci_dev_close_sync+0xbae/0x1060 net/bluetooth/hci_sync.c:5176
       hci_dev_do_close net/bluetooth/hci_core.c:561 [inline]
       hci_dev_close+0x112/0x210 net/bluetooth/hci_core.c:586
       sock_do_ioctl+0x158/0x460 net/socket.c:1222
       sock_ioctl+0x629/0x8e0 net/socket.c:1341
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:907 [inline]
       __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&hdev->req_lock);
                               lock((work_completion)(&hdev->cmd_sync_work));
                               lock(&hdev->req_lock);
  lock((work_completion)(&hdev->cmd_sync_work));

 *** DEADLOCK ***

2 locks held by syz-executor.0/5889:
 #0: ffff88802c7c1060 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:559 [inline]
 #0: ffff88802c7c1060 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_close+0x10a/0x210 net/bluetooth/hci_core.c:586
 #1: ffffffff8e333da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #1: ffffffff8e333da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #1: ffffffff8e333da0 (rcu_read_lock){....}-{1:2}, at: start_flush_work kernel/workqueue.c:4122 [inline]
 #1: ffffffff8e333da0 (rcu_read_lock){....}-{1:2}, at: __flush_work+0xe6/0xd00 kernel/workqueue.c:4181

stack backtrace:
CPU: 1 PID: 5889 Comm: syz-executor.0 Not tainted 6.9.0-rc6-next-20240430-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 touch_work_lockdep_map kernel/workqueue.c:3894 [inline]
 start_flush_work kernel/workqueue.c:4148 [inline]
 __flush_work+0x73c/0xd00 kernel/workqueue.c:4181
 __cancel_work_sync+0xbc/0x110 kernel/workqueue.c:4331
 hci_cmd_sync_clear+0x30/0x220 net/bluetooth/hci_sync.c:588
 hci_dev_close_sync+0xbae/0x1060 net/bluetooth/hci_sync.c:5176
 hci_dev_do_close net/bluetooth/hci_core.c:561 [inline]
 hci_dev_close+0x112/0x210 net/bluetooth/hci_core.c:586
 sock_do_ioctl+0x158/0x460 net/socket.c:1222
 sock_ioctl+0x629/0x8e0 net/socket.c:1341
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f65fea7dea9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f65ff76a0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f65febabf80 RCX: 00007f65fea7dea9
RDX: 0000000000000000 RSI: 00000000400448ca RDI: 0000000000000004
RBP: 00007f65feaca4a4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f65febabf80 R15: 00007ffcec22a898
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/01 03:11 linux-next d04466706db5 9e0e6af1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in hci_dev_close
2024/04/26 22:44 linux-next bb7a2467e6be 059e9963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in hci_dev_close
* Struck through repros no longer work on HEAD.