WARNING: ODEBUG bug in do_arpt_get_ctl

[syzbot]

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: syzbot+9d1c0d...@syzkaller.appspotmail.com
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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[Eric Biggers]

Like the similar bug report "WARNING: ODEBUG bug in do_ipt_get_ctl" [1], this
report doesn't make sense as there is no work_struct in the array being freed.
And this last occurred 4 months ago. So I am invalidating this one too as it
probably was a weird bug elsewhere in the kernel that has since been fixed:

#syz invalid

[1] https://groups.google.com/forum/#!msg/syzkaller-bugs/A_gWpsvtxKc/5YSSVpImDQAJ

- Eric