syzbot


INFO: task hung in hci_cmd_sync_clear (2)

Status: upstream: reported syz repro on 2025/01/26 06:48
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+bb555a2060a46486fa24@syzkaller.appspotmail.com
First crash: 371d, last: 30d
Fix bisection: failed (error log, bisect log)
  
Bug presence (2)
Date Name Commit Repro Result
2025/03/11 linux-6.1.y (ToT) 6ae7ac5c4251 syz [report] INFO: task hung in hci_cmd_sync_clear
2025/03/10 upstream (ToT) 4d872d51bc9d syz Didn't crash
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in hci_cmd_sync_clear bluetooth 1 4 1262d 1409d 0/29 auto-obsoleted due to no activity on 2022/11/16 14:10
linux-6.1 INFO: task hung in hci_cmd_sync_clear 1 1 686d 686d 0/3 auto-obsoleted due to no activity on 2024/06/24 21:55
upstream INFO: task hung in hci_cmd_sync_clear (2) bluetooth 1 15 677d 1083d 0/29 auto-obsoleted due to no activity on 2024/06/23 16:01
upstream INFO: task hung in hci_cmd_sync_clear (3) bluetooth 1 syz done 77 22h40m 449d 0/29 upstream: reported syz repro on 2024/11/09 06:00
Fix bisection attempts (2)
Created Duration User Patch Repo Result
2025/11/06 12:49 1h52m fix candidate upstream OK (0) job log
2025/06/27 09:52 17m bisect fix linux-6.1.y error job log

Sample crash report:
INFO: task syz-executor:4443 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:0     pid:4443  ppid:1      flags:0x0000000d
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0xddc/0x1b18 kernel/sched/core.c:6561
 schedule+0xc4/0x170 kernel/sched/core.c:6637
 schedule_timeout+0xb4/0x2cc kernel/time/timer.c:2144
 do_wait_for_common+0x284/0x3e4 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x44/0x5c kernel/sched/completion.c:138
 __flush_work+0x128/0x1bc kernel/workqueue.c:3076
 __cancel_work_timer+0x2ec/0x448 kernel/workqueue.c:3163
 cancel_work_sync+0x24/0x38 kernel/workqueue.c:3199
 hci_cmd_sync_clear+0x38/0x1e4 net/bluetooth/hci_sync.c:668
 hci_unregister_dev+0x170/0x4b4 net/bluetooth/hci_core.c:2701
 vhci_release+0x7c/0xcc drivers/bluetooth/hci_vhci.c:573
 __fput+0x1bc/0x7c0 fs/file_table.c:320
 ____fput+0x20/0x30 fs/file_table.c:348
 task_work_run+0x1ec/0x270 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x54c/0x19a8 kernel/exit.c:880
 do_group_exit+0x194/0x22c kernel/exit.c:1022
 get_signal+0x11d0/0x1310 kernel/signal.c:2871
 do_signal arch/arm64/kernel/signal.c:1081 [inline]
 do_notify_resume+0x34c/0x2b28 arch/arm64/kernel/signal.c:1134
 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+0x98/0x138 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffff800015227d70 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffff800015228590 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffff800015227400 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:349
3 locks held by kworker/u5:0/47:
 #0: ffff0000f035d938 ((wq_completion)hci0){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff80001cd97c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000dbc390b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
2 locks held by getty/4077:
 #0: ffff0000d65b3098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff80001ce162f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x2ec/0xf9c drivers/tty/n_tty.c:2198
2 locks held by kworker/u4:5/4391:
3 locks held by kworker/u5:1/4413:
 #0: ffff0000c3c10938 ((wq_completion)hci1){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800020917c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000d4dcd0b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:2/4415:
 #0: ffff0000d75db938 ((wq_completion)hci2){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800020aa7c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000d371d0b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/1:15/4599:
 #0: ffff0000d5ed4138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800021047c20 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff8000176bb748 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:74
3 locks held by kworker/1:17/4601:
 #0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800021067c20 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000eb29e240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x1c8/0x263c drivers/net/netdevsim/fib.c:1491
3 locks held by kworker/u5:5/5787:
 #0: ffff0000f1f53138 ((wq_completion)hci3){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800020dd7c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000ddd810b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:6/5857:
 #0: ffff0000da810138 ((wq_completion)hci13){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff8000211e7c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000fb0a90b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:7/6491:
 #0: ffff0000ef425138 ((wq_completion)hci10){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff8000218e7c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000f855d0b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:8/7025:
 #0: ffff0000d4cde138 ((wq_completion)hci4){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800021127c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000d37910b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:9/7647:
 #0: ffff0000c2c62938 ((wq_completion)hci5){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800020f87c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000dbaad0b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:10/7707:
 #0: ffff0000d8fe7938 ((wq_completion)hci6){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800021817c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000f1dc50b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:11/8295:
 #0: ffff0000d78ac138 ((wq_completion)hci7){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800021327c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000f55290b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:12/8925:
 #0: ffff0000db913138 ((wq_completion)hci8){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800021827c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000d31490b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:13/9567:
 #0: ffff0000f09df138 ((wq_completion)hci9){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff8000217f7c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000f749d0b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:14/10172:
 #0: ffff0000da812938 ((wq_completion)hci13#2){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff8000259d7c20 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000fb0a8078 (&hdev->lock){+.+.}-{3:3}, at: hci_le_create_big_complete_evt+0xc0/0x800 net/bluetooth/hci_event.c:6872
3 locks held by kworker/u5:15/10888:
 #0: ffff0000d3601138 ((wq_completion)hci11){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800021b57c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000f86f10b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
3 locks held by kworker/u5:16/11432:
 #0: ffff0000cad4a938 ((wq_completion)hci12){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff8000218f7c20 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
 #2: ffff0000fa1110b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x184/0x33c net/bluetooth/hci_sync.c:321
1 lock held by syz-executor/13245:
 #0: ffff8000176bb748 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffff8000176bb748 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x6ec/0xce4 net/core/rtnetlink.c:6147

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Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/01 11:10 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in hci_cmd_sync_clear
2025/12/30 02:11 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in hci_cmd_sync_clear
2025/01/26 06:47 linux-6.1.y 75cefdf153f5 9fbd772e .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in hci_cmd_sync_clear
* Struck through repros no longer work on HEAD.