Subject: WARNING: ODEBUG bug in do_arpt_get_ctl

From: syzbot <[email-masked]>
Date: Wed, 21 Feb 2018 12:59:03 -0800

Hello,

syzbot hit the following crash on upstream commit
91ab883eb21325ad80f3473633f794c78ac87f51 (Mon Feb 19 01:29:42 2018 +0000)
Linux 4.16-rc2

syzkaller reproducer is attached.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
------------[ cut here ]------------
ODEBUG: free active (active state 0) object type: work_struct hint:  
htable_gc+0x0/0xc0 net/netfilter/xt_hashlimit.c:376
WARNING: CPU: 1 PID: 4165 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: 4165 Comm: syz-executor3 Not tainted 4.16.0-rc2+ #320
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+0x58/0x80 arch/x86/entry/entry_64.S:957
RIP: 0010:debug_print_object+0x166/0x220 lib/debugobjects.c:288
RSP: 0018:ffff8801b3d8f790 EFLAGS: 00010082
RAX: dffffc0000000008 RBX: 0000000000000003 RCX: ffffffff815abdbe
RDX: 0000000000000000 RSI: 1ffff100367b1ea2 RDI: 1ffff100367b1e77
RBP: ffff8801b3d8f7d0 R08: 0000000000000000 R09: 1ffff100367b1e49
R10: ffffed00367b1f21 R11: ffffffff86b394b8 R12: 0000000000000001
R13: ffffffff86b14d80 R14: ffffffff86007de0 R15: ffffffff8147ac00
  __debug_check_no_obj_freed lib/debugobjects.c:745 [inline]
  debug_check_no_obj_freed+0x662/0xf1f lib/debugobjects.c:774
  __vunmap+0x112/0x380 mm/vmalloc.c:1530
  vfree+0x50/0xe0 mm/vmalloc.c:1606
  copy_entries_to_user net/ipv4/netfilter/arp_tables.c:714 [inline]
  get_entries net/ipv4/netfilter/arp_tables.c:867 [inline]
  do_arpt_get_ctl+0x7c4/0xa00 net/ipv4/netfilter/arp_tables.c:1485
  nf_sockopt net/netfilter/nf_sockopt.c:104 [inline]
  nf_getsockopt+0x6a/0xc0 net/netfilter/nf_sockopt.c:122
  ip_getsockopt+0x15c/0x220 net/ipv4/ip_sockglue.c:1571
  tcp_getsockopt+0x82/0xd0 net/ipv4/tcp.c:3359
  sock_common_getsockopt+0x95/0xd0 net/core/sock.c:2934
  SYSC_getsockopt net/socket.c:1880 [inline]
  SyS_getsockopt+0x178/0x340 net/socket.c:1862
  do_syscall_64+0x280/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45687a
RSP: 002b:0000000000a3eb48 EFLAGS: 00000212 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 0000000000000027 RCX: 000000000045687a
RDX: 0000000000000061 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000a3f200 R08: 0000000000a3eb7c R09: 0000000000000001
R10: 0000000000a3f200 R11: 0000000000000212 R12: 0000000000a3eb80
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000001380

======================================================
WARNING: possible circular locking dependency detected
4.16.0-rc2+ #320 Not tainted
------------------------------------------------------
syz-executor3/4165 is trying to acquire lock:
  ((console_sem).lock){..-.}, at: [<00000000d9ab369e>]  
down_trylock+0x13/0x70 kernel/locking/semaphore.c:136

but task is already holding lock:
  (&obj_hash[i].lock){-.-.}, at: [<00000000ab7f4c5c>]  
__debug_check_no_obj_freed lib/debugobjects.c:736 [inline]
  (&obj_hash[i].lock){-.-.}, at: [<00000000ab7f4c5c>]  
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:5352
        sched_init+0xb19/0xc43 kernel/sched/core.c:6049
        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:407

-> #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
        __vunmap+0x112/0x380 mm/vmalloc.c:1530
        vfree+0x50/0xe0 mm/vmalloc.c:1606
        copy_entries_to_user net/ipv4/netfilter/arp_tables.c:714 [inline]
        get_entries net/ipv4/netfilter/arp_tables.c:867 [inline]
        do_arpt_get_ctl+0x7c4/0xa00 net/ipv4/netfilter/arp_tables.c:1485
        nf_sockopt net/netfilter/nf_sockopt.c:104 [inline]
        nf_getsockopt+0x6a/0xc0 net/netfilter/nf_sockopt.c:122
        ip_getsockopt+0x15c/0x220 net/ipv4/ip_sockglue.c:1571
        tcp_getsockopt+0x82/0xd0 net/ipv4/tcp.c:3359
        sock_common_getsockopt+0x95/0xd0 net/core/sock.c:2934
        SYSC_getsockopt net/socket.c:1880 [inline]
        SyS_getsockopt+0x178/0x340 net/socket.c:1862
        do_syscall_64+0x280/0x940 arch/x86/entry/common.c:287
        entry_SYSCALL_64_after_hwframe+0x42/0xb7

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 ***

3 locks held by syz-executor3/4165:
  #0:  (sk_lock-AF_INET){+.+.}, at: [<000000005eb92c50>] lock_sock  
include/net/sock.h:1463 [inline]
  #0:  (sk_lock-AF_INET){+.+.}, at: [<000000005eb92c50>]  
ip_getsockopt+0x143/0x220 net/ipv4/ip_sockglue.c:1570
  #1:  (&xt[i].mutex){+.+.}, at: [<00000000c1964dfe>]  
xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1046
  #2:  (&obj_hash[i].lock){-.-.}, at: [<00000000ab7f4c5c>]  
__debug_check_no_obj_freed lib/debugobjects.c:736 [inline]
  #2:  (&obj_hash[i].lock){-.-.}, at: [<00000000ab7f4c5c>]  
debug_check_no_obj_freed+0x1e9/0xf1f lib/debugobjects.c:774

stack backtrace:
CPU: 1 PID: 4165 Comm: syz-executor3 Not tainted 4.16.0-rc2+ #320
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
  __vunmap+0x112/0x380 mm/vmalloc.c:1530
  vfree+0x50/0xe0 mm/vmalloc.c:1606
  copy_entries_to_user net/ipv4/netfilter/arp_tables.c:714 [inline]
  get_entries net/ipv4/netfilter/arp_tables.c:867 [inline]
  do_arpt_get_ctl+0x7c4/0xa00 net/ipv4/netfilter/arp_tables.c:1485
  nf_sockopt net/netfilter/nf_sockopt.c:104 [inline]
  nf_getsockopt+0x6a/0xc0 net/netfilter/nf_sockopt.c:122
  ip_getsockopt+0x15c/0x220 net/ipv4/ip_sockglue.c:1571
  tcp_getsockopt+0x82/0xd0 net/ipv4/tcp.c:3359
  sock_common_getsockopt+0x95/0xd0 net/core/sock.c:2934
  SYSC_getsockopt net/socket.c:1880 [inline]
  SyS_getsockopt+0x178/0x340 net/socket.c:1862
  do_syscall_64+0x280/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45687a
RSP: 002b:0000000000a3eb48 EFLAGS: 00000212 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 0000000000000027 RCX: 000000000045687a
RDX: 0000000000000061 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000a3f200 R08: 0000000000a3eb7c R09: 0000000000000001
R10: 0000000000a3f200 R11: 0000000000000212 R12: 0000000000a3eb80
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000001380
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..

---
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