l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=10) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=10) returned -9
l2tp_core: tunl 4: sockfd_lookup(fd=9) returned -9
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3c66/0x5270 kernel/locking/lockdep.c:3092
Read of size 8 at addr ffff8801d481a2a0 by task syz-executor0/4334

CPU: 0 PID: 4334 Comm: syz-executor0 Not tainted 4.4.131-gaa3863d #39
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 23a522f15ccc75f3 ffff8801d521f620 ffffffff81e0df8d
 ffffea0007520600 ffff8801d481a2a0 0000000000000000 ffff8801d481a2a0
 0000000000000000 ffff8801d521f658 ffffffff8151520c ffff8801d481a2a0
Call Trace:
 [<ffffffff81e0df8d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0df8d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8151520c>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff8151552b>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8151552b>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f9024>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff81232a76>] __lock_acquire+0x3c66/0x5270 kernel/locking/lockdep.c:3092
 [<ffffffff8123585e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
 [<ffffffff838bf0fa>] __raw_spin_lock_bh include/linux/spinlock_api_smp.h:137 [inline]
 [<ffffffff838bf0fa>] _raw_spin_lock_bh+0x3a/0x50 kernel/locking/spinlock.c:175
 [<ffffffff82f254a3>] spin_lock_bh include/linux/spinlock.h:307 [inline]
 [<ffffffff82f254a3>] lock_sock_nested+0x43/0x120 net/core/sock.c:2451
 [<ffffffff835a5220>] lock_sock include/net/sock.h:1493 [inline]
 [<ffffffff835a5220>] pppol2tp_release+0x50/0x310 net/l2tp/l2tp_ppp.c:493
 [<ffffffff82f18c96>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f18dd6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff815225f5>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81522b35>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bb8f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff81135175>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81135175>] do_exit+0x9e5/0x26b0 kernel/exit.c:759
 [<ffffffff8113b0c1>] do_group_exit+0x111/0x330 kernel/exit.c:889
 [<ffffffff8115e45c>] get_signal+0x4ec/0x14b0 kernel/signal.c:2317
 [<ffffffff8100e02b>] do_signal+0x8b/0x1d30 arch/x86/kernel/signal.c:712
 [<ffffffff8100360a>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:248
 [<ffffffff81007090>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81007090>] syscall_return_slowpath arch/x86/entry/common.c:348 [inline]
 [<ffffffff81007090>] do_syscall_32_irqs_on arch/x86/entry/common.c:398 [inline]
 [<ffffffff81007090>] do_fast_syscall_32+0x620/0x8b0 arch/x86/entry/common.c:459
 [<ffffffff838c17aa>] sysenter_flags_fixed+0xd/0x17

Allocated by task 4335:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f80d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f83b7>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f83b7>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f4ad4>] __kmalloc+0x124/0x310 mm/slub.c:3613
 [<ffffffff82f24364>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff82f24364>] sk_prot_alloc+0x204/0x300 net/core/sock.c:1354
 [<ffffffff82f29d3a>] sk_alloc+0x3a/0x3a0 net/core/sock.c:1419
 [<ffffffff835a1143>] pppol2tp_create+0x33/0x1f0 net/l2tp/l2tp_ppp.c:551
 [<ffffffff828f0e56>] pppox_create+0xf6/0x200 drivers/net/ppp/pppox.c:121
 [<ffffffff82f1f1c0>] __sock_create+0x2f0/0x5f0 net/socket.c:1177
 [<ffffffff82f1f6f0>] sock_create net/socket.c:1217 [inline]
 [<ffffffff82f1f6f0>] SYSC_socket net/socket.c:1247 [inline]
 [<ffffffff82f1f6f0>] SyS_socket+0xf0/0x1b0 net/socket.c:1227
 [<ffffffff81006d96>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d96>] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:459
 [<ffffffff838c17aa>] sysenter_flags_fixed+0xd/0x17

Freed by task 4335:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f80d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8a02>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8a02>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f5f04>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f5f04>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f5f04>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f5f04>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff82f2e1e7>] sk_prot_free net/core/sock.c:1391 [inline]
 [<ffffffff82f2e1e7>] sk_destruct+0x407/0x4c0 net/core/sock.c:1472
 [<ffffffff82f2e3fe>] __sk_free+0x15e/0x220 net/core/sock.c:1480
 [<ffffffff82f2e4f0>] sk_free+0x30/0x40 net/core/sock.c:1491
 [<ffffffff835a46ff>] sock_put include/net/sock.h:1639 [inline]
 [<ffffffff835a46ff>] pppol2tp_session_sock_put+0x5f/0x70 net/l2tp/l2tp_ppp.c:286
 [<ffffffff8359cf7c>] l2tp_tunnel_closeall+0x23c/0x350 net/l2tp/l2tp_core.c:1277
 [<ffffffff8359db0b>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff83490101>] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421
 [<ffffffff82f2e56d>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff8348edb5>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832f6a6f>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff83419600>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424
 [<ffffffff82f18c96>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f18dd6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff815225f5>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81522b35>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bb8f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff8100362d>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100362d>] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:252
 [<ffffffff81007090>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81007090>] syscall_return_slowpath arch/x86/entry/common.c:348 [inline]
 [<ffffffff81007090>] do_syscall_32_irqs_on arch/x86/entry/common.c:398 [inline]
 [<ffffffff81007090>] do_fast_syscall_32+0x620/0x8b0 arch/x86/entry/common.c:459
 [<ffffffff838c17aa>] sysenter_flags_fixed+0xd/0x17

The buggy address belongs to the object at ffff8801d481a200
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 160 bytes inside of
 2048-byte region [ffff8801d481a200, ffff8801d481aa00)
The buggy address belongs to the page:
BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<          (null)>]           (null)
PGD b27d4067 PUD b1253067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.131-gaa3863d #39
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9a41800 task.stack: ffff8801d9a50000
RIP: 0010:[<0000000000000000>]  [<          (null)>]           (null)
RSP: 0018:ffff8801db307f08  EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8801d9a57cf8 RCX: 1ffffffff0942911
RDX: 1ffff1003a95d0ac RSI: ffff8801d9a57cf8 RDI: ffff8801d4ae8500
RBP: ffff8801db307f70 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffff8801d9a41800 R12: ffff8801d4ae8500
R13: ffff8801d9a57d90 R14: ffff8801d9a50000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000bbaa4000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff81015b06 ffff8801db307f40 ffff8801db307f58 ffffffff81e6db1b
 0000000000000001 ffffffff83a08cc0 00000000000000a1 0000000000000001
 ffff8801d9a57cf8 00000000000000a1 ffff8801d4ae8500 00000000000000a1
Call Trace:
 <IRQ> 
 [<ffffffff838c28d9>] do_IRQ+0x89/0x1c0 arch/x86/kernel/irq.c:239
 [<ffffffff838c09e0>] common_interrupt+0xa0/0xa0 arch/x86/entry/entry_64.S:596
 <EOI> 
 [<ffffffff81025da5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81025da5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:290
 [<ffffffff810272f0>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:281
 [<ffffffff8121b9e7>] default_idle_call+0x57/0x70 kernel/sched/idle.c:93
 [<ffffffff8121c18f>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff8121c18f>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff8121c18f>] cpu_startup_entry+0x6af/0x780 kernel/sched/idle.c:301
 [<ffffffff810aa174>] start_secondary+0x324/0x400 arch/x86/kernel/smpboot.c:242
Code:  Bad RIP value.
RIP  [<          (null)>]           (null)
 RSP <ffff8801db307f08>
CR2: 0000000000000000
---[ end trace 0fbef14cafd8e36c ]---