syzbot


possible deadlock in sco_sock_timeout (2)

Status: upstream: reported on 2024/04/07 02:01
Reported-by: syzbot+43013a84c1d2e6b30c48@syzkaller.appspotmail.com
First crash: 78d, last: 48d
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in sco_sock_timeout bluetooth 1 623d 623d 0/27 auto-obsoleted due to no activity on 2023/02/07 11:14
linux-5.15 possible deadlock in sco_sock_timeout 2 322d 340d 0/3 auto-obsoleted due to no activity on 2023/11/15 21:15
linux-6.1 possible deadlock in sco_sock_timeout 2 345d 364d 0/3 auto-obsoleted due to no activity on 2023/10/23 03:23

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.1.90-syzkaller #0 Not tainted
------------------------------------------------------
kworker/1:11/4475 is trying to acquire lock:
ffff88805b555130 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1748 [inline]
ffff88805b555130 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_timeout+0xbd/0x230 net/bluetooth/sco.c:97

but task is already holding lock:
ffffc90015317d20 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __flush_work+0xfe/0xad0 kernel/workqueue.c:3072
       __cancel_work_timer+0x519/0x6a0 kernel/workqueue.c:3163
       sco_conn_del+0x205/0x300 net/bluetooth/sco.c:205
       hci_disconn_cfm include/net/bluetooth/hci_core.h:1808 [inline]
       hci_conn_hash_flush+0x10e/0x2a0 net/bluetooth/hci_conn.c:2441
       hci_dev_close_sync+0x9a9/0x1020 net/bluetooth/hci_sync.c:5018
       hci_dev_do_close net/bluetooth/hci_core.c:554 [inline]
       hci_rfkill_set_block+0x131/0x200 net/bluetooth/hci_core.c:956
       rfkill_set_block+0x1e7/0x430 net/rfkill/core.c:345
       rfkill_fop_write+0x5b7/0x790 net/rfkill/core.c:1286
       vfs_write+0x2d9/0xba0 fs/read_write.c:582
       ksys_write+0x19c/0x2c0 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (hci_cb_list_lock){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       hci_connect_cfm include/net/bluetooth/hci_core.h:1790 [inline]
       hci_remote_features_evt+0x664/0xab0 net/bluetooth/hci_event.c:3803
       hci_event_func net/bluetooth/hci_event.c:7539 [inline]
       hci_event_packet+0xa9d/0x1510 net/bluetooth/hci_event.c:7591
       hci_rx_work+0x3cd/0xce0 net/bluetooth/hci_core.c:4130
       process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
       worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
       kthread+0x28d/0x320 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

-> #1 (&hdev->lock){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       sco_sock_connect+0x181/0x8f0 net/bluetooth/sco.c:593
       __sys_connect_file net/socket.c:2006 [inline]
       __sys_connect+0x2c9/0x300 net/socket.c:2023
       __do_sys_connect net/socket.c:2033 [inline]
       __se_sys_connect net/socket.c:2030 [inline]
       __x64_sys_connect+0x76/0x80 net/socket.c:2030
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       lock_sock_nested+0x44/0x100 net/core/sock.c:3485
       lock_sock include/net/sock.h:1748 [inline]
       sco_sock_timeout+0xbd/0x230 net/bluetooth/sco.c:97
       process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
       worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
       kthread+0x28d/0x320 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

other info that might help us debug this:

Chain exists of:
  sk_lock-AF_BLUETOOTH-BTPROTO_SCO --> hci_cb_list_lock --> (work_completion)(&(&conn->timeout_work)->work)

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((work_completion)(&(&conn->timeout_work)->work));
                               lock(hci_cb_list_lock);
                               lock((work_completion)(&(&conn->timeout_work)->work));
  lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO);

 *** DEADLOCK ***

2 locks held by kworker/1:11/4475:
 #0: ffff888012470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #1: ffffc90015317d20 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267

stack backtrace:
CPU: 1 PID: 4475 Comm: kworker/1:11 Not tainted 6.1.90-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: events sco_sock_timeout
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 lock_sock_nested+0x44/0x100 net/core/sock.c:3485
 lock_sock include/net/sock.h:1748 [inline]
 sco_sock_timeout+0xbd/0x230 net/bluetooth/sco.c:97
 process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/07 07:03 linux-6.1.y 909ba1f1b414 fa7a5cf0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in sco_sock_timeout
2024/04/07 02:00 linux-6.1.y 347385861c50 ca620dd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in sco_sock_timeout
2024/04/07 02:00 linux-6.1.y 347385861c50 ca620dd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in sco_sock_timeout
* Struck through repros no longer work on HEAD.