syzbot

ODEBUG: free active (active state 0) object type: timer_list hint: led_timeout_callback+0x0/0x20 include/linux/compiler.h:210
WARNING: CPU: 1 PID: 4163 at lib/debugobjects.c:291 debug_print_object+0x166/0x220 lib/debugobjects.c:288
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 4163 Comm: syzkaller832372 Not tainted 4.16.0-rc1+ #310
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 panic+0x1e4/0x41c kernel/panic.c:183
 __warn+0x1dc/0x200 kernel/panic.c:547
 report_bug+0x211/0x2d0 lib/bug.c:184
 fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
 fixup_bug arch/x86/kernel/traps.c:247 [inline]
 do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:988
RIP: 0010:debug_print_object+0x166/0x220 lib/debugobjects.c:288
RSP: 0018:ffff8801b83f7630 EFLAGS: 00010082
RAX: dffffc0000000008 RBX: 0000000000000003 RCX: ffffffff815aaf5e
RDX: 0000000000000000 RSI: 1ffff1003707ee76 RDI: 1ffff1003707ee4b
RBP: ffff8801b83f7670 R08: 0000000000000000 R09: 1ffff1003707ee1d
R10: ffffed003707eef5 R11: ffffffff86b39478 R12: 0000000000000001
R13: ffffffff86b4ace0 R14: ffffffff86007c60 R15: ffffffff815fd9c0
 __debug_check_no_obj_freed lib/debugobjects.c:745 [inline]
 debug_check_no_obj_freed+0x662/0xf1f lib/debugobjects.c:774
 kfree+0xc7/0x260 mm/slab.c:3799
 led_tg_destroy+0x28a/0x3f0 net/netfilter/xt_LED.c:192
 cleanup_entry+0x218/0x350 net/ipv4/netfilter/ip_tables.c:654
 __do_replace+0x79d/0xa50 net/ipv4/netfilter/ip_tables.c:1089
 do_replace net/ipv4/netfilter/ip_tables.c:1145 [inline]
 do_ipt_set_ctl+0x40f/0x5f0 net/ipv4/netfilter/ip_tables.c:1675
 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
 nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
 ip_setsockopt+0x97/0xa0 net/ipv4/ip_sockglue.c:1259
 tcp_setsockopt+0x82/0xd0 net/ipv4/tcp.c:2905
 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2975
 SYSC_setsockopt net/socket.c:1849 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1828
 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x26/0x9b
RIP: 0033:0x444aca
RSP: 002b:00007ffc5c5e38e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000006cf9c0 RCX: 0000000000444aca
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00000000006cf9c0 R08: 00000000000002d8 R09: 0000000000004000
R10: 00000000006cf960 R11: 0000000000000206 R12: 00007ffc5c5e3910
R13: 00000000006d1b80 R14: 0000000000000003 R15: 0000000000000000

======================================================
WARNING: possible circular locking dependency detected
4.16.0-rc1+ #310 Not tainted
------------------------------------------------------
syzkaller832372/4163 is trying to acquire lock:
 ((console_sem).lock){..-.}, at: [<0000000039fb4208>] down_trylock+0x13/0x70 kernel/locking/semaphore.c:136

but task is already holding lock:
 (&obj_hash[i].lock){-.-.}, at: [<0000000056d2f8d2>] __debug_check_no_obj_freed lib/debugobjects.c:736 [inline]
 (&obj_hash[i].lock){-.-.}, at: [<0000000056d2f8d2>] debug_check_no_obj_freed+0x1e9/0xf1f lib/debugobjects.c:774

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+0x96/0xc0 kernel/locking/spinlock.c:152
       __debug_object_init+0x109/0x1040 lib/debugobjects.c:343
       debug_object_init+0x17/0x20 lib/debugobjects.c:391
       debug_hrtimer_init kernel/time/hrtimer.c:410 [inline]
       debug_init kernel/time/hrtimer.c:458 [inline]
       hrtimer_init+0x8c/0x410 kernel/time/hrtimer.c:1259
       init_dl_task_timer+0x1b/0x50 kernel/sched/deadline.c:1060
       __sched_fork+0x2bb/0xb60 kernel/sched/core.c:2189
       init_idle+0x75/0x820 kernel/sched/core.c:5347
       sched_init+0xb19/0xc43 kernel/sched/core.c:6044
       start_kernel+0x452/0x819 init/main.c:585
       x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378
       x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359
       secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237

-> #2 (&rq->lock){-.-.}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
       _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144
       rq_lock kernel/sched/sched.h:1760 [inline]
       task_fork_fair+0x7a/0x690 kernel/sched/fair.c:9471
       sched_fork+0x450/0xc10 kernel/sched/core.c:2405
       copy_process.part.37+0x1758/0x4b60 kernel/fork.c:1774
       copy_process kernel/fork.c:1617 [inline]
       _do_fork+0x1f7/0xf70 kernel/fork.c:2098
       kernel_thread+0x34/0x40 kernel/fork.c:2157
       rest_init+0x22/0xf0 init/main.c:402
       start_kernel+0x7f1/0x819 init/main.c:716
       x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378
       x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359
       secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237

-> #1 (&p->pi_lock){-.-.}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
       try_to_wake_up+0xbc/0x15f0 kernel/sched/core.c:1989
       wake_up_process+0x10/0x20 kernel/sched/core.c:2152
       __up.isra.0+0x1cc/0x2c0 kernel/locking/semaphore.c:262
       up+0x13b/0x1d0 kernel/locking/semaphore.c:187
       __up_console_sem+0xb2/0x1a0 kernel/printk/printk.c:242
       console_unlock+0x5af/0xfb0 kernel/printk/printk.c:2417
       vprintk_emit+0x5c3/0xb90 kernel/printk/printk.c:1907
       vprintk_default+0x28/0x30 kernel/printk/printk.c:1947
       vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
       printk+0xaa/0xca kernel/printk/printk.c:1980
       kauditd_printk_skb kernel/audit.c:506 [inline]
       kauditd_hold_skb+0x163/0x180 kernel/audit.c:539
       kauditd_send_queue+0xfa/0x140 kernel/audit.c:702
       kauditd_thread+0x660/0x940 kernel/audit.c:828
       kthread+0x33c/0x400 kernel/kthread.c:238
       ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429

-> #0 ((console_sem).lock){..-.}:
       lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
       down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
       __down_trylock_console_sem+0xa2/0x1e0 kernel/printk/printk.c:225
       console_trylock+0x15/0x70 kernel/printk/printk.c:2229
       console_trylock_spinning kernel/printk/printk.c:1643 [inline]
       vprintk_emit+0x5b5/0xb90 kernel/printk/printk.c:1906
       vprintk_default+0x28/0x30 kernel/printk/printk.c:1947
       vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
       printk+0xaa/0xca kernel/printk/printk.c:1980
       __warn_printk+0x90/0xf0 kernel/panic.c:599
       debug_print_object+0x166/0x220 lib/debugobjects.c:288
       __debug_check_no_obj_freed lib/debugobjects.c:745 [inline]
       debug_check_no_obj_freed+0x662/0xf1f lib/debugobjects.c:774
       kfree+0xc7/0x260 mm/slab.c:3799
       led_tg_destroy+0x28a/0x3f0 net/netfilter/xt_LED.c:192
       cleanup_entry+0x218/0x350 net/ipv4/netfilter/ip_tables.c:654
       __do_replace+0x79d/0xa50 net/ipv4/netfilter/ip_tables.c:1089
       do_replace net/ipv4/netfilter/ip_tables.c:1145 [inline]
       do_ipt_set_ctl+0x40f/0x5f0 net/ipv4/netfilter/ip_tables.c:1675
       nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
       nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
       ip_setsockopt+0x97/0xa0 net/ipv4/ip_sockglue.c:1259
       tcp_setsockopt+0x82/0xd0 net/ipv4/tcp.c:2905
       sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2975
       SYSC_setsockopt net/socket.c:1849 [inline]
       SyS_setsockopt+0x189/0x360 net/socket.c:1828
       do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
       entry_SYSCALL_64_after_hwframe+0x26/0x9b

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 ***

2 locks held by syzkaller832372/4163:
 #0:  (&xt[i].mutex){+.+.}, at: [<000000000bde75ab>] xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1046
 #1:  (&obj_hash[i].lock){-.-.}, at: [<0000000056d2f8d2>] __debug_check_no_obj_freed lib/debugobjects.c:736 [inline]
 #1:  (&obj_hash[i].lock){-.-.}, at: [<0000000056d2f8d2>] debug_check_no_obj_freed+0x1e9/0xf1f lib/debugobjects.c:774

stack backtrace:
CPU: 1 PID: 4163 Comm: syzkaller832372 Not tainted 4.16.0-rc1+ #310
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 print_circular_bug.isra.38+0x2cd/0x2dc kernel/locking/lockdep.c:1223
 check_prev_add kernel/locking/lockdep.c:1863 [inline]
 check_prevs_add kernel/locking/lockdep.c:1976 [inline]
 validate_chain kernel/locking/lockdep.c:2417 [inline]
 __lock_acquire+0x30a8/0x3e00 kernel/locking/lockdep.c:3431
 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
 down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
 __down_trylock_console_sem+0xa2/0x1e0 kernel/printk/printk.c:225
 console_trylock+0x15/0x70 kernel/printk/printk.c:2229
 console_trylock_spinning kernel/printk/printk.c:1643 [inline]
 vprintk_emit+0x5b5/0xb90 kernel/printk/printk.c:1906
 vprintk_default+0x28/0x30 kernel/printk/printk.c:1947
 vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
 printk+0xaa/0xca kernel/printk/printk.c:1980
 __warn_printk+0x90/0xf0 kernel/panic.c:599
 debug_print_object+0x166/0x220 lib/debugobjects.c:288
 __debug_check_no_obj_freed lib/debugobjects.c:745 [inline]
 debug_check_no_obj_freed+0x662/0xf1f lib/debugobjects.c:774
 kfree+0xc7/0x260 mm/slab.c:3799
 led_tg_destroy+0x28a/0x3f0 net/netfilter/xt_LED.c:192
 cleanup_entry+0x218/0x350 net/ipv4/netfilter/ip_tables.c:654
 __do_replace+0x79d/0xa50 net/ipv4/netfilter/ip_tables.c:1089
 do_replace net/ipv4/netfilter/ip_tables.c:1145 [inline]
 do_ipt_set_ctl+0x40f/0x5f0 net/ipv4/netfilter/ip_tables.c:1675
 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
 nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
 ip_setsockopt+0x97/0xa0 net/ipv4/ip_sockglue.c:1259
 tcp_setsockopt+0x82/0xd0 net/ipv4/tcp.c:2905
 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2975
 SYSC_setsockopt net/socket.c:1849 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1828
 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x26/0x9b
RIP: 0033:0x444aca
RSP: 002b:00007ffc5c5e38e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000006cf9c0 RCX: 0000000000444aca
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00000000006cf9c0 R08: 00000000000002d8 R09: 0000000000004000
R10: 00000000006cf960 R11: 0000000000000206 R12: 00007ffc5c5e3910
R13: 00000000006d1b80 R14: 0000000000000003 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..