syzbot


INFO: task hung in hci_req_sync

Status: fixed on 2021/11/10 00:50
Reported-by: syzbot+be2baed593ea56c6a84c@syzkaller.appspotmail.com
Fix commit: f41a4b2b5eb7 Bluetooth: add timeout sanity check to hci_inquiry
First crash: 425d, last: 425d

Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: INFO: task hung in hci_req_sync (log)
Repro: C syz .config
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 INFO: task hung in hci_req_sync C error 3 168d 770d 0/1 upstream: reported C repro on 2020/08/28 10:54
linux-4.19 INFO: task hung in hci_req_sync C error 7 381d 770d 0/1 upstream: reported C repro on 2020/08/28 04:41
Patch testing requests:
Created Duration User Patch Repo Result
2021/08/16 21:04 18m paskripkin@gmail.com patch upstream OK
2021/08/16 20:00 4m paskripkin@gmail.com patch upstream error

Sample crash report:
INFO: task syz-executor446:8489 blocked for more than 143 seconds.
      Not tainted 5.14.0-rc4-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor446 state:D stack:28712 pid: 8489 ppid:  8452 flags:0x00000000
Call Trace:
 context_switch kernel/sched/core.c:4683 [inline]
 __schedule+0x93a/0x26f0 kernel/sched/core.c:5940
 schedule+0xd3/0x270 kernel/sched/core.c:6019
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6078
 __mutex_lock_common kernel/locking/mutex.c:1036 [inline]
 __mutex_lock+0x7b6/0x10a0 kernel/locking/mutex.c:1104
 hci_req_sync+0x33/0xd0 net/bluetooth/hci_request.c:276
 hci_inquiry+0x6f4/0x9e0 net/bluetooth/hci_core.c:1357
 hci_sock_ioctl+0x1a7/0x910 net/bluetooth/hci_sock.c:1060
 sock_do_ioctl+0xcb/0x2d0 net/socket.c:1094
 sock_ioctl+0x477/0x6a0 net/socket.c:1221
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x446449
RSP: 002b:00007f36ab8342e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004cb400 RCX: 0000000000446449
RDX: 00000000200000c0 RSI: 00000000800448f0 RDI: 0000000000000004
RBP: 00000000004cb40c R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000004 R14: 00007f36ab8346b8 R15: 00000000004cb408
INFO: task syz-executor446:8491 blocked for more than 143 seconds.
      Not tainted 5.14.0-rc4-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor446 state:D stack:28176 pid: 8491 ppid:  8452 flags:0x00000004
Call Trace:
 context_switch kernel/sched/core.c:4683 [inline]
 __schedule+0x93a/0x26f0 kernel/sched/core.c:5940
 schedule+0xd3/0x270 kernel/sched/core.c:6019
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6078
 __mutex_lock_common kernel/locking/mutex.c:1036 [inline]
 __mutex_lock+0x7b6/0x10a0 kernel/locking/mutex.c:1104
 hci_req_sync+0x33/0xd0 net/bluetooth/hci_request.c:276
 hci_inquiry+0x6f4/0x9e0 net/bluetooth/hci_core.c:1357
 hci_sock_ioctl+0x1a7/0x910 net/bluetooth/hci_sock.c:1060
 sock_do_ioctl+0xcb/0x2d0 net/socket.c:1094
 sock_ioctl+0x477/0x6a0 net/socket.c:1221
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x446449
RSP: 002b:00007f36ab8342e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004cb400 RCX: 0000000000446449
RDX: 00000000200000c0 RSI: 00000000800448f0 RDI: 0000000000000004
RBP: 00000000004cb40c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000004 R14: 00007f36ab8346b8 R15: 00000000004cb408

Showing all locks held in the system:
6 locks held by kworker/u4:0/8:
1 lock held by khungtaskd/1635:
 #0: ffffffff8b97c180 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6446
1 lock held by in:imklog/8352:
 #0: ffff888033e1d4f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:974
1 lock held by syz-executor446/8486:
 #0: ffff8880349c4ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_req_sync+0x33/0xd0 net/bluetooth/hci_request.c:276
1 lock held by syz-executor446/8489:
 #0: ffff8880349c4ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_req_sync+0x33/0xd0 net/bluetooth/hci_request.c:276
1 lock held by syz-executor446/8491:
 #0: ffff8880349c4ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_req_sync+0x33/0xd0 net/bluetooth/hci_request.c:276

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 1635 Comm: khungtaskd Not tainted 5.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
 watchdog+0xd0a/0xfc0 kernel/hung_task.c:295
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 8 Comm: kworker/u4:0 Not tainted 5.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0x452/0xc20 kernel/smp.c:967
Code: 0b 00 85 ed 74 4d 48 b8 00 00 00 00 00 fc ff df 4d 89 f4 4c 89 f5 49 c1 ec 03 83 e5 07 49 01 c4 83 c5 03 e8 d0 47 0b 00 f3 90 <41> 0f b6 04 24 40 38 c5 7c 08 84 c0 0f 85 33 06 00 00 8b 43 08 31
RSP: 0018:ffffc90000cd7a00 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffff8880b9d570c0 RCX: 0000000000000000
RDX: ffff88813fe6d4c0 RSI: ffffffff816a6400 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff816a6426 R11: 0000000000000000 R12: ffffed10173aae19
R13: 0000000000000001 R14: ffff8880b9d570c8 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f56e8f43000 CR3: 000000000b68e000 CR4: 0000000000350ef0
Call Trace:
 on_each_cpu_cond_mask+0x56/0xa0 kernel/smp.c:1133
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:929 [inline]
 text_poke_bp_batch+0x47d/0x560 arch/x86/kernel/alternative.c:1183
 text_poke_flush arch/x86/kernel/alternative.c:1268 [inline]
 text_poke_flush arch/x86/kernel/alternative.c:1265 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1275
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 jump_label_update+0x1d5/0x430 kernel/jump_label.c:830
 static_key_enable_cpuslocked+0x1b1/0x260 kernel/jump_label.c:177
 static_key_enable+0x16/0x20 kernel/jump_label.c:190
 toggle_allocation_gate mm/kfence/core.c:623 [inline]
 toggle_allocation_gate+0x100/0x390 mm/kfence/core.c:615
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-root 2021/08/08 06:03 upstream c9194f32bfd9 6972b106 .config log report syz C INFO: task hung in hci_req_sync
* Struck through repros no longer work on HEAD.