Re: WARNING in __debug_object_init (3)

[Dmitry Vyukov]

On Sun, Oct 28, 2018 at 3:18 AM, syzbot
<syzbot+6e682caa546b7c96c859@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    8c60c36d0b8c Add linux-next specific files for 20181019
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=100feec5400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8b6d7c4c81535e89
> dashboard link: https://syzkaller.appspot.com/bug?extid=6e682caa546b7c96c859
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13579abd400000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13654f6b400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+6e682caa546b7c96c859@xxxxxxxxxxxxxxxxxxxxxxxxx

+Eric knows what's wrong here. Something about "bpf: add tests for
direct packet access from CGROUP_SKB" commit. Was is amended to fix a
bug?


> ODEBUG: object 0000000015e9012c is on stack 00000000115bcb67, but NOT
> annotated.
> WARNING: CPU: 0 PID: 5594 at lib/debugobjects.c:369 debug_object_is_on_stack
> lib/debugobjects.c:363 [inline]
> WARNING: CPU: 0 PID: 5594 at lib/debugobjects.c:369
> __debug_object_init.cold.14+0x51/0xdf lib/debugobjects.c:395
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 5594 Comm: syz-executor740 Not tainted 4.19.0-rc8-next-20181019+
> #98
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x244/0x39d lib/dump_stack.c:113
>  panic+0x2ad/0x55c kernel/panic.c:188
>  __warn.cold.8+0x20/0x45 kernel/panic.c:540
>  report_bug+0x254/0x2d0 lib/bug.c:186
>  fixup_bug arch/x86/kernel/traps.c:178 [inline]
>  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
>  do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
>  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969
> RIP: 0010:debug_object_is_on_stack lib/debugobjects.c:363 [inline]
> RIP: 0010:__debug_object_init.cold.14+0x51/0xdf lib/debugobjects.c:395
> Code: ea 03 80 3c 02 00 75 7c 49 8b 54 24 18 48 89 de 48 c7 c7 c0 f1 40 88
> 4c 89 85 d0 fd ff ff e8 09 8c d1 fd 4c 8b 85 d0 fd ff ff <0f> 0b e9 09 d6 ff
> ff 41 83 c4 01 b8 ff ff 37 00 44 89 25 b7 4e 66
> RSP: 0018:ffff8801bb387308 EFLAGS: 00010086
> RAX: 0000000000000050 RBX: ffff8801bb387af8 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff816585a5 RDI: 0000000000000005
> RBP: ffff8801bb387560 R08: ffff8801cb208a20 R09: ffffed003b5c5008
> R10: ffffed003b5c5008 R11: ffff8801dae28047 R12: ffff8801d82ea300
> R13: 0000000000069700 R14: ffff8801d82ea300 R15: ffff8801cb208a10
>  debug_object_init+0x16/0x20 lib/debugobjects.c:432
>  debug_timer_init kernel/time/timer.c:704 [inline]
>  debug_init kernel/time/timer.c:757 [inline]
>  init_timer_key+0xa9/0x480 kernel/time/timer.c:806
>  sock_init_data+0xe1/0xdc0 net/core/sock.c:2696
>  bpf_prog_test_run_skb+0x255/0xc40 net/bpf/test_run.c:144
>  bpf_prog_test_run+0x130/0x1a0 kernel/bpf/syscall.c:1790
>  __do_sys_bpf kernel/bpf/syscall.c:2427 [inline]
>  __se_sys_bpf kernel/bpf/syscall.c:2371 [inline]
>  __x64_sys_bpf+0x3d8/0x510 kernel/bpf/syscall.c:2371
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x440259
> Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffc212cf818 EFLAGS: 00000213 ORIG_RAX: 0000000000000141
> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440259
> RDX: 0000000000000028 RSI: 0000000020000080 RDI: 000000000000000a
> RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
> R10: 0000000000000000 R11: 0000000000000213 R12: 0000000000401ae0
> R13: 0000000000401b70 R14: 0000000000000000 R15: 0000000000000000
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 4.19.0-rc8-next-20181019+ #98 Not tainted
> ------------------------------------------------------
> syz-executor740/5594 is trying to acquire lock:
> 00000000688fcc6b ((console_sem).lock){-.-.}, at: down_trylock+0x13/0x70
> kernel/locking/semaphore.c:136
>
> but task is already holding lock:
> 00000000505ead1b (&obj_hash[i].lock){-.-.}, at:
> __debug_object_init+0x127/0x1290 lib/debugobjects.c:384
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #3 (&obj_hash[i].lock){-.-.}:
>        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>        _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
>        __debug_object_init+0x127/0x1290 lib/debugobjects.c:384
>        debug_object_init+0x16/0x20 lib/debugobjects.c:432
>        debug_hrtimer_init kernel/time/hrtimer.c:410 [inline]
>        debug_init kernel/time/hrtimer.c:458 [inline]
>        hrtimer_init+0x97/0x490 kernel/time/hrtimer.c:1308
>        init_dl_task_timer+0x1b/0x50 kernel/sched/deadline.c:1057
>        __sched_fork+0x2ae/0x590 kernel/sched/core.c:2166
>        init_idle+0x75/0x740 kernel/sched/core.c:5382
>        sched_init+0xb33/0xc02 kernel/sched/core.c:6065
>        start_kernel+0x4be/0xa2b init/main.c:608
>        x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:472
>        x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:451
>        secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243
>
> -> #2 (&rq->lock){-.-.}:
>        __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
>        _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
>        rq_lock kernel/sched/sched.h:1127 [inline]
>        task_fork_fair+0xb0/0x6d0 kernel/sched/fair.c:9768
>        sched_fork+0x443/0xba0 kernel/sched/core.c:2359
>        copy_process+0x2585/0x8770 kernel/fork.c:1887
>        _do_fork+0x1cb/0x11c0 kernel/fork.c:2216
>        kernel_thread+0x34/0x40 kernel/fork.c:2275
>        rest_init+0x28/0x372 init/main.c:409
>        arch_call_rest_init+0xe/0x1b
>        start_kernel+0x9f0/0xa2b init/main.c:745
>        x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:472
>        x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:451
>        secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243
>
> -> #1 (&p->pi_lock){-.-.}:
>        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>        _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
>        try_to_wake_up+0xd2/0x12e0 kernel/sched/core.c:1965
>        wake_up_process+0x10/0x20 kernel/sched/core.c:2129
>        __up.isra.1+0x1c0/0x2a0 kernel/locking/semaphore.c:262
>        up+0x13c/0x1c0 kernel/locking/semaphore.c:187
>        __up_console_sem+0xbe/0x1b0 kernel/printk/printk.c:236
>        console_unlock+0x80c/0x1190 kernel/printk/printk.c:2432
>        vprintk_emit+0x391/0x990 kernel/printk/printk.c:1922
>        vprintk_default+0x28/0x30 kernel/printk/printk.c:1964
>        vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
>        printk+0xa7/0xcf kernel/printk/printk.c:1997
>        check_stack_usage kernel/exit.c:755 [inline]
>        do_exit.cold.18+0x57/0x16f kernel/exit.c:916
>        do_group_exit+0x177/0x440 kernel/exit.c:970
>        __do_sys_exit_group kernel/exit.c:981 [inline]
>        __se_sys_exit_group kernel/exit.c:979 [inline]
>        __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:979
>        do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>        entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> -> #0 ((console_sem).lock){-.-.}:
>        lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
>        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>        _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
>        down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
>        __down_trylock_console_sem+0xae/0x1f0 kernel/printk/printk.c:219
>        console_trylock+0x15/0xa0 kernel/printk/printk.c:2247
>        console_trylock_spinning kernel/printk/printk.c:1653 [inline]
>        vprintk_emit+0x372/0x990 kernel/printk/printk.c:1921
>        vprintk_default+0x28/0x30 kernel/printk/printk.c:1964
>        vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
>        printk+0xa7/0xcf kernel/printk/printk.c:1997
>        debug_object_is_on_stack lib/debugobjects.c:363 [inline]
>        __debug_object_init.cold.14+0x4a/0xdf lib/debugobjects.c:395
>        debug_object_init+0x16/0x20 lib/debugobjects.c:432
>        debug_timer_init kernel/time/timer.c:704 [inline]
>        debug_init kernel/time/timer.c:757 [inline]
>        init_timer_key+0xa9/0x480 kernel/time/timer.c:806
>        sock_init_data+0xe1/0xdc0 net/core/sock.c:2696
>        bpf_prog_test_run_skb+0x255/0xc40 net/bpf/test_run.c:144
>        bpf_prog_test_run+0x130/0x1a0 kernel/bpf/syscall.c:1790
>        __do_sys_bpf kernel/bpf/syscall.c:2427 [inline]
>        __se_sys_bpf kernel/bpf/syscall.c:2371 [inline]
>        __x64_sys_bpf+0x3d8/0x510 kernel/bpf/syscall.c:2371
>        do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>        entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> other info that might help us debug this:
>
> Chain exists of:
>   (console_sem).lock --> &rq->lock --> &obj_hash[i].lock
>
>  Possible unsafe locking scenario:
>
>        CPU0                    CPU1
>        ----                    ----
>   lock(&obj_hash[i].lock);
>                                lock(&rq->lock);
>                                lock(&obj_hash[i].lock);
>   lock((console_sem).lock);
>
>  *** DEADLOCK ***
>
> 1 lock held by syz-executor740/5594:
>  #0: 00000000505ead1b (&obj_hash[i].lock){-.-.}, at:
> __debug_object_init+0x127/0x1290 lib/debugobjects.c:384
>
> stack backtrace:
> CPU: 0 PID: 5594 Comm: syz-executor740 Not tainted 4.19.0-rc8-next-20181019+
> #98
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x244/0x39d lib/dump_stack.c:113
>  print_circular_bug.isra.35.cold.54+0x1bd/0x27d
> kernel/locking/lockdep.c:1221
>  check_prev_add kernel/locking/lockdep.c:1863 [inline]
>  check_prevs_add kernel/locking/lockdep.c:1976 [inline]
>  validate_chain kernel/locking/lockdep.c:2347 [inline]
>  __lock_acquire+0x3399/0x4c20 kernel/locking/lockdep.c:3341
>  lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
>  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>  _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
>  down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
>  __down_trylock_console_sem+0xae/0x1f0 kernel/printk/printk.c:219
>  console_trylock+0x15/0xa0 kernel/printk/printk.c:2247
>  console_trylock_spinning kernel/printk/printk.c:1653 [inline]
>  vprintk_emit+0x372/0x990 kernel/printk/printk.c:1921
>  vprintk_default+0x28/0x30 kernel/printk/printk.c:1964
>  vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
>  printk+0xa7/0xcf kernel/printk/printk.c:1997
>  debug_object_is_on_stack lib/debugobjects.c:363 [inline]
>  __debug_object_init.cold.14+0x4a/0xdf lib/debugobjects.c:395
>  debug_object_init+0x16/0x20 lib/debugobjects.c:432
>  debug_timer_init kernel/time/timer.c:704 [inline]
>  debug_init kernel/time/timer.c:757 [inline]
>  init_timer_key+0xa9/0x480 kernel/time/timer.c:806
>  sock_init_data+0xe1/0xdc0 net/core/sock.c:2696
>  bpf_prog_test_run_skb+0x255/0xc40 net/bpf/test_run.c:144
>  bpf_prog_test_run+0x130/0x1a0 kernel/bpf/syscall.c:1790
>  __do_sys_bpf kernel/bpf/syscall.c:2427 [inline]
>  __se_sys_bpf kernel/bpf/syscall.c:2371 [inline]
>  __x64_sys_bpf+0x3d8/0x510 kernel/bpf/syscall.c:2371
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x440259
> Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffc212cf818 EFLAGS: 00000213 ORIG_RAX: 0000000000000141
> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440259
> RDX: 0000000000000028 RSI: 0000000020000080 RDI: 000000000000000a
> RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
> R10: 0000000000000000 R11: 0000000000000213 R12: 0000000000401ae0
> R13: 0000000000401b70 R14: 0000000000000000 R15: 0000000000000000
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
>
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>
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