netlink: 20 bytes leftover after parsing attributes in process `syz-executor6'.
netlink: 20 bytes leftover after parsing attributes in process `syz-executor6'.
BUG: sleeping function called from invalid context at net/core/sock.c:2502
in_atomic(): 1, irqs_disabled(): 0, pid: 8885, name: syz-executor6
2 locks held by syz-executor6/8885:
 #0:  (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff8301830b>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff8301830b>] __sock_release+0x8b/0x260 net/socket.c:604
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] __rcu_reclaim kernel/rcu/rcu.h:108 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] rcu_process_callbacks+0x98e/0x12b0 kernel/rcu/tree.c:3037
Preemption disabled at:[  150.493241] [<ffffffff81f23bac>] debug_object_activate+0x11c/0x4e0 lib/debugobjects.c:407
CPU: 1 PID: 8885 Comm: syz-executor6 Not tainted 4.9.124-g6a1b592 #30
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db307cd8 ffffffff81eb95e9 ffffffff81f23bac 0000000000000000
 0000000000000101 ffff8801d519e000 ffff8801d519e000 ffff8801db307d10
 ffffffff81426851 ffff8801d519e000 ffffffff840f88a0 00000000000009c6
Call Trace:
 <IRQ> [  150.545448]  [<ffffffff81eb95e9>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [  150.545448]  [<ffffffff81eb95e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81426851>] ___might_sleep.cold.123+0x1bc/0x1f5 kernel/sched/core.c:7988
 [<ffffffff811bd9a5>] __might_sleep+0x95/0x1a0 kernel/sched/core.c:7945
 [<ffffffff8302b774>] lock_sock_nested+0x34/0x120 net/core/sock.c:2502
 [<ffffffff83428dd9>] lock_sock include/net/sock.h:1404 [inline]
 [<ffffffff83428dd9>] inet_shutdown+0x69/0x360 net/ipv4/af_inet.c:823
 [<ffffffff836cb740>] pppol2tp_session_close+0xa0/0xe0 net/l2tp/l2tp_ppp.c:441
 [<ffffffff836c4f71>] l2tp_tunnel_closeall+0x231/0x350 net/l2tp/l2tp_core.c:1368
 [<ffffffff836c57f2>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1324
 [<ffffffff830281f5>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff812899ee>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff812899ee>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff812899ee>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff812899ee>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff812899ee>] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037
 [<ffffffff83a085c0>] __do_softirq+0x210/0x940 kernel/softirq.c:288
 [<ffffffff8114d554>] invoke_softirq kernel/softirq.c:368 [inline]
 [<ffffffff8114d554>] irq_exit+0x114/0x150 kernel/softirq.c:409
 [<ffffffff83a071a1>] exiting_irq arch/x86/include/asm/apic.h:669 [inline]
 [<ffffffff83a071a1>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:962
 [<ffffffff83a03330>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> [  150.676274]  [<ffffffff83a010ff>] ? arch_local_irq_restore arch/x86/include/asm/paravirt.h:768 [inline]
 <EOI> [  150.676274]  [<ffffffff83a010ff>] ? __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:162 [inline]
 <EOI> [  150.676274]  [<ffffffff83a010ff>] ? _raw_spin_unlock_irqrestore+0x5f/0x70 kernel/locking/spinlock.c:191
 [<ffffffff81f23c8d>] debug_object_activate+0x1fd/0x4e0 lib/debugobjects.c:437
 [<ffffffff812887e5>] debug_rcu_head_queue kernel/rcu/rcu.h:75 [inline]
 [<ffffffff812887e5>] __call_rcu.constprop.69+0x35/0x910 kernel/rcu/tree.c:3138
 [<ffffffff812890d2>] call_rcu+0x12/0x20 kernel/rcu/tree_plugin.h:655
 [<ffffffff831d70f2>] netlink_release+0x4b2/0xaa0 net/netlink/af_netlink.c:790
 [<ffffffff83018357>] __sock_release+0xd7/0x260 net/socket.c:605
 [<ffffffff830184f9>] sock_close+0x19/0x20 net/socket.c:1059
 [<ffffffff8157ca73>] __fput+0x263/0x700 fs/file_table.c:208
 [<ffffffff8157cf95>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8119a66c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff8100559c>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:161
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<ffffffff83a019d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

=================================
[ INFO: inconsistent lock state ]
4.9.124-g6a1b592 #30 Tainted: G        W      
---------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
syz-executor6/8885 [HC0[0]:SC1[3]:HE1:SE0] takes:
 (sk_lock-AF_PPPOX){+.?.+.}, at: [<ffffffff83428dd9>] lock_sock include/net/sock.h:1404 [inline]
 (sk_lock-AF_PPPOX){+.?.+.}, at: [<ffffffff83428dd9>] inet_shutdown+0x69/0x360 net/ipv4/af_inet.c:823
  mark_held_locks+0xc7/0x130 kernel/locking/lockdep.c:2660
  __trace_hardirqs_on_caller kernel/locking/lockdep.c:2689 [inline]
  trace_hardirqs_on_caller+0x38b/0x590 kernel/locking/lockdep.c:2736
  trace_hardirqs_on+0xd/0x10 kernel/locking/lockdep.c:2743
  __local_bh_enable_ip+0x6a/0xd0 kernel/softirq.c:190
  local_bh_enable include/linux/bottom_half.h:31 [inline]
  lock_sock_nested+0xdc/0x120 net/core/sock.c:2512
  lock_sock include/net/sock.h:1404 [inline]
  pppol2tp_connect+0xd9/0x18f0 net/l2tp/l2tp_ppp.c:590
  SYSC_connect+0x1b8/0x300 net/socket.c:1575
  SyS_connect+0x24/0x30 net/socket.c:1556
  do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
  entry_SYSCALL_64_after_swapgs+0x5d/0xdb
irq event stamp: 1928
hardirqs last  enabled at (1928): [<ffffffff83a02369>] restore_regs_and_iret+0x0/0x1d
hardirqs last disabled at (1927): [<ffffffff83a0332b>] apic_timer_interrupt+0x9b/0xb0 arch/x86/entry/entry_64.S:648
softirqs last  enabled at (1616): [<ffffffff831d70b4>] sock_net include/net/sock.h:2207 [inline]
softirqs last  enabled at (1616): [<ffffffff831d70b4>] netlink_release+0x474/0xaa0 net/netlink/af_netlink.c:788
softirqs last disabled at (1621): [<ffffffff8114d554>] invoke_softirq kernel/softirq.c:368 [inline]
softirqs last disabled at (1621): [<ffffffff8114d554>] irq_exit+0x114/0x150 kernel/softirq.c:409

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(sk_lock-AF_PPPOX);
  <Interrupt>
    lock(sk_lock-AF_PPPOX);

 *** DEADLOCK ***

2 locks held by syz-executor6/8885:
 #0:  (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff8301830b>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff8301830b>] __sock_release+0x8b/0x260 net/socket.c:604
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] __rcu_reclaim kernel/rcu/rcu.h:108 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81289ace>] rcu_process_callbacks+0x98e/0x12b0 kernel/rcu/tree.c:3037

stack backtrace:
CPU: 1 PID: 8885 Comm: syz-executor6 Tainted: G        W       4.9.124-g6a1b592 #30
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db307a58 ffffffff81eb95e9 ffff8801d519e000 ffffffff856011c0
 ffff8801d519e918 ffff8801d519e938 0000000000000000 ffff8801db307ac8
 ffffffff81429ccd 0000000000000003 0000000000000001 ffff880100000000
Call Trace:
 <IRQ> [  151.028172]  [<ffffffff81eb95e9>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [  151.028172]  [<ffffffff81eb95e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81429ccd>] print_usage_bug.cold.57+0x327/0x421 kernel/locking/lockdep.c:2387
 [<ffffffff81237726>] valid_state kernel/locking/lockdep.c:2400 [inline]
 [<ffffffff81237726>] mark_lock_irq kernel/locking/lockdep.c:2602 [inline]
 [<ffffffff81237726>] mark_lock+0xcc6/0x1280 kernel/locking/lockdep.c:3065
 [<ffffffff812390f0>] mark_irqflags kernel/locking/lockdep.c:2923 [inline]
 [<ffffffff812390f0>] __lock_acquire+0xd40/0x4070 kernel/locking/lockdep.c:3302
 [<ffffffff8123ce90>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff8302b806>] lock_sock_nested+0xc6/0x120 net/core/sock.c:2511
 [<ffffffff83428dd9>] lock_sock include/net/sock.h:1404 [inline]
 [<ffffffff83428dd9>] inet_shutdown+0x69/0x360 net/ipv4/af_inet.c:823
 [<ffffffff836cb740>] pppol2tp_session_close+0xa0/0xe0 net/l2tp/l2tp_ppp.c:441
 [<ffffffff836c4f71>] l2tp_tunnel_closeall+0x231/0x350 net/l2tp/l2tp_core.c:1368
 [<ffffffff836c57f2>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1324
 [<ffffffff830281f5>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff812899ee>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff812899ee>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff812899ee>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff812899ee>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff812899ee>] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037
 [<ffffffff83a085c0>] __do_softirq+0x210/0x940 kernel/softirq.c:288
 [<ffffffff8114d554>] invoke_softirq kernel/softirq.c:368 [inline]
 [<ffffffff8114d554>] irq_exit+0x114/0x150 kernel/softirq.c:409
 [<ffffffff83a071a1>] exiting_irq arch/x86/include/asm/apic.h:669 [inline]
 [<ffffffff83a071a1>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:962
 [<ffffffff83a03330>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> [  151.199447]  [<ffffffff83a010ff>] ? arch_local_irq_restore arch/x86/include/asm/paravirt.h:768 [inline]
 <EOI> [  151.199447]  [<ffffffff83a010ff>] ? __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:162 [inline]
 <EOI> [  151.199447]  [<ffffffff83a010ff>] ? _raw_spin_unlock_irqrestore+0x5f/0x70 kernel/locking/spinlock.c:191
 [<ffffffff81f23c8d>] debug_object_activate+0x1fd/0x4e0 lib/debugobjects.c:437
 [<ffffffff812887e5>] debug_rcu_head_queue kernel/rcu/rcu.h:75 [inline]
 [<ffffffff812887e5>] __call_rcu.constprop.69+0x35/0x910 kernel/rcu/tree.c:3138
 [<ffffffff812890d2>] call_rcu+0x12/0x20 kernel/rcu/tree_plugin.h:655
 [<ffffffff831d70f2>] netlink_release+0x4b2/0xaa0 net/netlink/af_netlink.c:790
 [<ffffffff83018357>] __sock_release+0xd7/0x260 net/socket.c:605
 [<ffffffff830184f9>] sock_close+0x19/0x20 net/socket.c:1059
 [<ffffffff8157ca73>] __fput+0x263/0x700 fs/file_table.c:208
 [<ffffffff8157cf95>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8119a66c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff8100559c>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:161
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<ffffffff83a019d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
IP: [<ffffffff836c473c>] l2tp_session_free+0x11c/0x200 net/l2tp/l2tp_core.c:1765
PGD 1ccd64067 [  151.332173] PUD 1d8868067 
Oops: 0002 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 8891 Comm: syz-executor1 Tainted: G        W       4.9.124-g6a1b592 #30
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d731e000 task.stack: ffff8801d4430000
RIP: 0010:[<ffffffff836c473c>]  [<ffffffff836c473c>] l2tp_session_free+0x11c/0x200 net/l2tp/l2tp_core.c:1765
RSP: 0018:ffff8801d4437a20  EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff8801d746b180 RCX: ffffc900020d2000
RDX: 1ffff1003b448700 RSI: ffffffff836c4711 RDI: ffff8801da243800
RBP: ffff8801d4437a40 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801da243680
R13: ffff8801d746b188 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f3a121d1700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 00000001d3c9b000 CR4: 00000000001606f0
Stack:
 ffff88019881a200 ffff8801d746b180 ffff88019881a5d0 ffff88019881a4d8
 ffff8801d4437a68 ffffffff836cc022 ffff88019881a640 ffff88019881a200
 ffffffff836cbf50 ffff8801d4437aa0 ffffffff830281f5 ffff88019881a640
Call Trace:
 [<ffffffff836cc022>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:297 [inline]
 [<ffffffff836cc022>] pppol2tp_session_destruct+0xd2/0x110 net/l2tp/l2tp_ppp.c:460
 [<ffffffff830281f5>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff8302fc83>] sk_destruct+0x63/0x80 net/core/sock.c:1463
 [<ffffffff8302fcef>] __sk_free+0x4f/0x220 net/core/sock.c:1471
 [<ffffffff8302feeb>] sk_free+0x2b/0x40 net/core/sock.c:1482
 [<ffffffff836cf329>] sock_put include/net/sock.h:1588 [inline]
 [<ffffffff836cf329>] pppol2tp_release+0x239/0x2e0 net/l2tp/l2tp_ppp.c:501
 [<ffffffff83018357>] __sock_release+0xd7/0x260 net/socket.c:605
 [<ffffffff830184f9>] sock_close+0x19/0x20 net/socket.c:1059
 [<ffffffff8157ca73>] __fput+0x263/0x700 fs/file_table.c:208
 [<ffffffff8157cf95>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8119a66c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff8116cd33>] get_signal+0x1133/0x1450 kernel/signal.c:2151
 [<ffffffff81052637>] do_signal+0x87/0x19f0 arch/x86/kernel/signal.c:807
 [<ffffffff81005581>] exit_to_usermode_loop+0xe1/0x120 arch/x86/entry/common.c:157
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<ffffffff83a019d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 49 8d bc 24 80 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c6 00 00 00 4d 8b b4 24 80 01 00 00 <f0> 41 ff 8e 80 00 00 00 74 69 e8 a5 c5 c9 fd 4c 89 ea 48 b8 00 
RIP  [<ffffffff836c473c>] l2tp_session_free+0x11c/0x200 net/l2tp/l2tp_core.c:1765
 RSP <ffff8801d4437a20>
CR2: 0000000000000080
---[ end trace 26181a33e9a77f3b ]---