Messages in this thread | | | Subject | Re: [syzbot] INFO: task hung in hci_req_sync | From | Pavel Skripkin <> | Date | Thu, 12 Aug 2021 12:49:08 +0300 |
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On 8/12/21 9:13 AM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: c9194f32bfd9 Merge tag 'ext4_for_linus_stable' of git://gi.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1488f59e300000 > kernel config: https://syzkaller.appspot.com/x/.config?x=343fd21f6f4da2d6 > dashboard link: https://syzkaller.appspot.com/bug?extid=be2baed593ea56c6a84c > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15b5afc6300000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15fcd192300000 > > Bisection is inconclusive: the issue happens on the oldest tested release. > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17dce4fa300000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=143ce4fa300000 > console output: https://syzkaller.appspot.com/x/log.txt?x=103ce4fa300000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+be2baed593ea56c6a84c@syzkaller.appspotmail.com > > 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 >
Looks like too big timeout is passed from ioctl:
C repro:
*(uint16_t*)0x200000c0 = 0; *(uint16_t*)0x200000c2 = 0; memcpy((void*)0x200000c4, "\xf0\x08\xa7", 3); *(uint8_t*)0x200000c7 = 0x81; <- ir.length *(uint8_t*)0x200000c8 = 0; syscall(__NR_ioctl, r[0], 0x800448f0, 0x200000c0ul);
Then ir.length * msecs_to_jiffies(2000) timeout is passed to hci_req_sync(). Task will stuck here
err = wait_event_interruptible_timeout(hdev->req_wait_q, hdev->req_status != HCI_REQ_PEND, timeout);
for 258 seconds (I guess, it's because of test environment, but, maybe, we should add sanity check for timeout value)
With regards, Pavel Skripkin
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