WARNING: ODEBUG bug in rfcomm_dlc_free

syzbot
2018-07-31T06:34:06Z

Hello,

syzbot found the following crash on:

HEAD commit: 527838d470e3 Merge branch 'x86-urgent-for-linus' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17ebce52400000
kernel config: https://syzkaller.appspot.com/x/.config?x=2dc0cd7c2eefb46f
dashboard link: https://syzkaller.appspot.com/bug?extid=1f6d4ad860c650c2f215
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1f6d4ad860c650c2f215@syzkaller.appspotmail.com

bond0: Error: Device is in use and cannot be enslaved
Unknown ioctl -1070573808
------------[ cut here ]------------
ODEBUG: free active (active state 0) object type: timer_list hint:
rfcomm_dlc_timeout+0x0/0x70 include/linux/list.h:64
WARNING: CPU: 0 PID: 1696 at lib/debugobjects.c:329
debug_print_object+0x16a/0x210 lib/debugobjects.c:326
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 1696 Comm: syz-executor4 Not tainted 4.18.0-rc7+ #170
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+0x1c9/0x2b4 lib/dump_stack.c:113
panic+0x238/0x4e7 kernel/panic.c:184
__warn.cold.8+0x163/0x1ba kernel/panic.c:536
report_bug+0x252/0x2d0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:debug_print_object+0x16a/0x210 lib/debugobjects.c:326
Code: 3a 87 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 92 00 00 00 48 8b 14 dd
20 74 3a 87 4c 89 f6 48 c7 c7 c0 69 3a 87 e8 c6 b0 e6 fd <0f> 0b 83 05 a9
e6 29 05 01 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffff880191937648 EFLAGS: 00010086
RAX: 0000000000000000 RBX: 0000000000000003 RCX: ffffc90007a4a000
RDX: 00000000000292e2 RSI: ffffffff81632481 RDI: 0000000000000001
RBP: ffff880191937688 R08: ffff8801b67b6340 R09: ffffed003b603ec2
R10: ffffed003b603ec2 R11: ffff8801db01f617 R12: 0000000000000001
R13: ffffffff87f9c9e0 R14: ffffffff873a6e60 R15: ffffffff816918a0
__debug_check_no_obj_freed lib/debugobjects.c:783 [inline]
debug_check_no_obj_freed+0x3b2/0x595 lib/debugobjects.c:815
kfree+0xc7/0x260 mm/slab.c:3812
rfcomm_dlc_free+0x1e/0x30 net/bluetooth/rfcomm/core.c:328
rfcomm_dlc_put include/net/bluetooth/rfcomm.h:258 [inline]
__rfcomm_create_dev net/bluetooth/rfcomm/tty.c:417 [inline]
rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
rfcomm_dev_ioctl+0x1dfe/0x2240 net/bluetooth/rfcomm/tty.c:588
rfcomm_sock_ioctl+0x89/0xb0 net/bluetooth/rfcomm/sock.c:902
sock_do_ioctl+0xe4/0x3e0 net/socket.c:969
sock_ioctl+0x30d/0x680 net/socket.c:1093
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:684
ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
__do_sys_ioctl fs/ioctl.c:708 [inline]
__se_sys_ioctl fs/ioctl.c:706 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x456a09
Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f521726dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f521726e6d4 RCX: 0000000000456a09
RDX: 0000000020000140 RSI: 00000000400452c8 RDI: 0000000000000014
RBP: 0000000000930140 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004cddc0 R14: 00000000004c472b R15: 0000000000000001

======================================================
WARNING: possible circular locking dependency detected
4.18.0-rc7+ #170 Not tainted
------------------------------------------------------
syz-executor4/1696 is trying to acquire lock:
0000000072b74d86 ((console_sem).lock){-.-.}, at: down_trylock+0x13/0x70
kernel/locking/semaphore.c:136

but task is already holding lock:
000000001082e10b (&obj_hash[i].lock){-.-.}, at: __debug_check_no_obj_freed
lib/debugobjects.c:774 [inline]
000000001082e10b (&obj_hash[i].lock){-.-.}, at:
debug_check_no_obj_freed+0x16c/0x595 lib/debugobjects.c:815

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+0x127/0x12e0 lib/debugobjects.c:381
debug_object_init+0x16/0x20 lib/debugobjects.c:429
debug_hrtimer_init kernel/time/hrtimer.c:410 [inline]
debug_init kernel/time/hrtimer.c:458 [inline]
hrtimer_init+0x97/0x480 kernel/time/hrtimer.c:1308
init_dl_task_timer+0x1b/0x50 kernel/sched/deadline.c:1056
__sched_fork+0x2ae/0x590 kernel/sched/core.c:2185
init_idle+0x75/0x7a0 kernel/sched/core.c:5405
sched_init+0xbf3/0xd2c kernel/sched/core.c:6103
start_kernel+0x47d/0x949 init/main.c:602
x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242

-> #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:1812 [inline]
task_fork_fair+0x93/0x680 kernel/sched/fair.c:9952
sched_fork+0x446/0xb40 kernel/sched/core.c:2381
copy_process.part.39+0x1bf5/0x70b0 kernel/fork.c:1796
copy_process kernel/fork.c:1639 [inline]
_do_fork+0x291/0x12a0 kernel/fork.c:2122
kernel_thread+0x34/0x40 kernel/fork.c:2181
rest_init+0x22/0xe4 init/main.c:408
start_kernel+0x90e/0x949 init/main.c:738
x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242

-> #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+0xd2/0x12a0 kernel/sched/core.c:1985
wake_up_process+0x10/0x20 kernel/sched/core.c:2148
__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:242
console_unlock+0x7a2/0x10b0 kernel/printk/printk.c:2411
vprintk_emit+0x6c6/0xdf0 kernel/printk/printk.c:1907
vprintk_default+0x28/0x30 kernel/printk/printk.c:1948
vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:382
printk+0xa7/0xcf kernel/printk/printk.c:1981
load_umh+0x51/0xbd net/bpfilter/bpfilter_kern.c:98
do_one_initcall+0x127/0x913 init/main.c:884
do_initcall_level init/main.c:952 [inline]
do_initcalls init/main.c:960 [inline]
do_basic_setup init/main.c:978 [inline]
kernel_init_freeable+0x49b/0x58e init/main.c:1135
kernel_init+0x11/0x1b3 init/main.c:1061
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

-> #0 ((console_sem).lock){-.-.}:
lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924
__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+0xae/0x200 kernel/printk/printk.c:225
console_trylock+0x15/0xa0 kernel/printk/printk.c:2230
console_trylock_spinning kernel/printk/printk.c:1643 [inline]
vprintk_emit+0x6ad/0xdf0 kernel/printk/printk.c:1906
vprintk_default+0x28/0x30 kernel/printk/printk.c:1948
vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:382
printk+0xa7/0xcf kernel/printk/printk.c:1981
__warn_printk+0x8c/0xe0 kernel/panic.c:590
debug_print_object+0x16a/0x210 lib/debugobjects.c:326
__debug_check_no_obj_freed lib/debugobjects.c:783 [inline]
debug_check_no_obj_freed+0x3b2/0x595 lib/debugobjects.c:815
kfree+0xc7/0x260 mm/slab.c:3812
rfcomm_dlc_free+0x1e/0x30 net/bluetooth/rfcomm/core.c:328
rfcomm_dlc_put include/net/bluetooth/rfcomm.h:258 [inline]
__rfcomm_create_dev net/bluetooth/rfcomm/tty.c:417 [inline]
rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
rfcomm_dev_ioctl+0x1dfe/0x2240 net/bluetooth/rfcomm/tty.c:588
rfcomm_sock_ioctl+0x89/0xb0 net/bluetooth/rfcomm/sock.c:902
sock_do_ioctl+0xe4/0x3e0 net/socket.c:969
sock_ioctl+0x30d/0x680 net/socket.c:1093
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:684
ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
__do_sys_ioctl fs/ioctl.c:708 [inline]
__se_sys_ioctl fs/ioctl.c:706 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
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 ***

3 locks held by syz-executor4/1696:
#0: 000000007adfc19a (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}, at:
lock_sock include/net/sock.h:1474 [inline]
#0: 000000007adfc19a (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}, at:
rfcomm_sock_ioctl+0x7b/0xb0 net/bluetooth/rfcomm/sock.c:901
#1: 00000000f97b5970 (rfcomm_ioctl_mutex){+.+.}, at: rfcomm_create_dev
net/bluetooth/rfcomm/tty.c:485 [inline]
#1: 00000000f97b5970 (rfcomm_ioctl_mutex){+.+.}, at:
rfcomm_dev_ioctl+0x4a5/0x2240 net/bluetooth/rfcomm/tty.c:588
#2: 000000001082e10b (&obj_hash[i].lock){-.-.}, at:
__debug_check_no_obj_freed lib/debugobjects.c:774 [inline]
#2: 000000001082e10b (&obj_hash[i].lock){-.-.}, at:
debug_check_no_obj_freed+0x16c/0x595 lib/debugobjects.c:815

stack backtrace:
CPU: 0 PID: 1696 Comm: syz-executor4 Not tainted 4.18.0-rc7+ #170
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+0x1c9/0x2b4 lib/dump_stack.c:113
print_circular_bug.isra.36.cold.57+0x1bd/0x27d
kernel/locking/lockdep.c:1227
check_prev_add kernel/locking/lockdep.c:1867 [inline]
check_prevs_add kernel/locking/lockdep.c:1980 [inline]
validate_chain kernel/locking/lockdep.c:2421 [inline]
__lock_acquire+0x3449/0x5020 kernel/locking/lockdep.c:3435
lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924
__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+0xae/0x200 kernel/printk/printk.c:225
console_trylock+0x15/0xa0 kernel/printk/printk.c:2230
console_trylock_spinning kernel/printk/printk.c:1643 [inline]
vprintk_emit+0x6ad/0xdf0 kernel/printk/printk.c:1906
vprintk_default+0x28/0x30 kernel/printk/printk.c:1948
vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:382
printk+0xa7/0xcf kernel/printk/printk.c:1981
__warn_printk+0x8c/0xe0 kernel/panic.c:590
debug_print_object+0x16a/0x210 lib/debugobjects.c:326
__debug_check_no_obj_freed lib/debugobjects.c:783 [inline]
debug_check_no_obj_freed+0x3b2/0x595 lib/debugobjects.c:815
kfree+0xc7/0x260 mm/slab.c:3812
rfcomm_dlc_free+0x1e/0x30 net/bluetooth/rfcomm/core.c:328
rfcomm_dlc_put include/net/bluetooth/rfcomm.h:258 [inline]
__rfcomm_create_dev net/bluetooth/rfcomm/tty.c:417 [inline]
rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
rfcomm_dev_ioctl+0x1dfe/0x2240 net/bluetooth/rfcomm/tty.c:588
rfcomm_sock_ioctl+0x89/0xb0 net/bluetooth/rfcomm/sock.c:902
sock_do_ioctl+0xe4/0x3e0 net/socket.c:969
sock_ioctl+0x30d/0x680 net/socket.c:1093
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:684
ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
__do_sys_ioctl fs/ioctl.c:708 [inline]
__se_sys_ioctl fs/ioctl.c:706 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x456a09
Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f521726dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f521726e6d4 RCX: 0000000000456a09
RDX: 0000000020000140 RSI: 00000000400452c8 RDI: 0000000000000014
RBP: 0000000000930140 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004cddc0 R14: 00000000004c472b R15: 0000000000000001
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..

---
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