syzbot


INFO: task hung in lo_compat_ioctl

Status: auto-closed as invalid on 2019/02/22 14:29
First crash: 2147d, last: 2147d

Sample crash report:
INFO: task syz-executor2:31660 blocked for more than 120 seconds.
      Not tainted 4.9.105-gd7e64f8 #43
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D29072 31660   3879 0x20020004
 ffff88019615b000 ffff8801b55939c0 ffff8801be1cea00 ffff8801a5dbc800
 ffff8801db321c18 ffff8801d6167be8 ffffffff839e8c1d ffff88019615b8c8
 ffffed0032c2b718 ffff88019615b000 00fffc0000000000 ffff8801db3224e8
Call Trace:
 [<ffffffff839ea21f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839eaba3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590
 [<ffffffff839ef026>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839ef026>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff825cc662>] lo_compat_ioctl+0xe2/0x140 drivers/block/loop.c:1528
 [<ffffffff81ea5955>] compat_blkdev_ioctl+0x3a5/0x3ad0 block/compat_ioctl.c:751
 [<ffffffff8168ee46>] C_SYSC_ioctl fs/compat_ioctl.c:1602 [inline]
 [<ffffffff8168ee46>] compat_SyS_ioctl+0x126/0x1fe0 fs/compat_ioctl.c:1549
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff839fb210>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

Showing all locks held in the system:
2 locks held by khungtaskd/520:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81366b9c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81366b9c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81426180>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3783:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7cc2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82120062>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor2/31660:
 #0:  (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<ffffffff825cc662>] lo_compat_ioctl+0xe2/0x140 drivers/block/loop.c:1528
1 lock held by syz-executor2/31661:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cab6b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by blkid/31653:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cab6b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

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

NMI backtrace for cpu 0
CPU: 0 PID: 520 Comm: khungtaskd Not tainted 4.9.105-gd7e64f8 #43
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d95afd08 ffffffff81eb41a9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b96a0 ffff8801d95afd40
 ffffffff81ebf4a7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb41a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb41a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf4a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf43a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b97a4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81367134>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81367134>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81367134>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81367134>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9cdc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 31652 Comm: syz-executor2 Not tainted 4.9.105-gd7e64f8 #43
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d78be000 task.stack: ffff8801cda60000
RIP: 0010:[<ffffffff8135eeeb>] c [<ffffffff8135eeeb>] __read_once_size include/linux/compiler.h:243 [inline]
RIP: 0010:[<ffffffff8135eeeb>] c [<ffffffff8135eeeb>] __sanitizer_cov_trace_pc+0x3b/0x50 kernel/kcov.c:105
RSP: 0018:ffff8801cda67c98  EFLAGS: 00000246
RAX: 0000000000040000 RBX: ffff8801cbffc690 RCX: ffffc9000293e000
RDX: 000000000003ffff RSI: ffffffff825cc06b RDI: ffff88018eb933b0
RBP: ffff8801cda67c98 R08: ffff8801d78be910 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff1003af17d1d R12: ffff8801cbffc690
R13: ffff8801d5d92280 R14: ffff8801d3823600 R15: ffff8801d3823758
FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000f5722b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000001d79000 CR3: 00000001d6db1000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801cda67d20c ffffffff825cc06bc ffff8801cda67ca8c ffff8801cda67ca8c
 ffff8801d3823750c 0000000000006000c ffff8801d3a301d0c ffff8801cbffc888c
 ffff8801cda40e00c ffff8801d5d92360c ffff88010002001dc ffff880100000000c
Call Trace:
 [<ffffffff825cc06b>] is_loop_device drivers/block/loop.c:704 [inline]
 [<ffffffff825cc06b>] loop_set_fd drivers/block/loop.c:886 [inline]
 [<ffffffff825cc06b>] lo_ioctl+0x158b/0x1aa0 drivers/block/loop.c:1347
 [<ffffffff825cc632>] lo_compat_ioctl+0xb2/0x140 drivers/block/loop.c:1540
 [<ffffffff81ea5955>] compat_blkdev_ioctl+0x3a5/0x3ad0 block/compat_ioctl.c:751
 [<ffffffff8168ee46>] C_SYSC_ioctl fs/compat_ioctl.c:1602 [inline]
 [<ffffffff8168ee46>] compat_SyS_ioctl+0x126/0x1fe0 fs/compat_ioctl.c:1549
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff839fb210>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
Code: c8c c8e ccb c7e c81 ce2 c00 c01 c1f c00 c48 c8b c75 c08 c75 c2b c8b c90 c80 c12 c00 c00 c83 cfa c02 c75 c20 c48 c8b c88 c88 c12 c00 c00 c8b c80 c84 c12 c00 c00 c48 c8b c11 c<48> c83 cc2 c01 c48 c39 cd0 c76 c07 c48 c89 c34 cd1 c48 c89 c11 c5d cc3 c0f c1f c00 c

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/06/01 20:47 https://android.googlesource.com/kernel/common android-4.9 d7e64f8022e4 2f93b54f .config console log report ci-android-49-kasan-gce-386
* Struck through repros no longer work on HEAD.