FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
IP: refcount_dec_and_test arch/x86/include/asm/refcount.h:75 [inline]
IP: sock_put include/net/sock.h:1657 [inline]
IP: l2tp_session_free+0x113/0x200 net/l2tp/l2tp_core.c:1714
PGD 21811a067 P4D 21811a067 PUD 21a96d067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 11740 Comm: syz-executor.2 Not tainted 4.14.175-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8882109ba6c0 task.stack: ffff888202a58000
RIP: 0010:refcount_dec_and_test arch/x86/include/asm/refcount.h:75 [inline]
RIP: 0010:sock_put include/net/sock.h:1657 [inline]
RIP: 0010:l2tp_session_free+0x113/0x200 net/l2tp/l2tp_core.c:1714
RSP: 0018:ffff888202a5fcd0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff8880a97dea80 RCX: 0000000000000000
RDX: 1ffff110152fbd81 RSI: ffff8882109baf40 RDI: ffff8880a97dec08
RBP: ffff8880a46f9280 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a46f9290
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880948ae510
FS:  0000000002be9940(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 000000020307a000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:300 [inline]
 pppol2tp_session_destruct+0xcd/0x110 net/l2tp/l2tp_ppp.c:460
 __sk_destruct+0x49/0x640 net/core/sock.c:1556
 sk_destruct+0x97/0xc0 net/core/sock.c:1596
 __sk_free+0x4c/0x220 net/core/sock.c:1604
 sk_free+0x2b/0x40 net/core/sock.c:1615
 sock_put include/net/sock.h:1658 [inline]
 pppol2tp_release+0x247/0x2f0 net/l2tp/l2tp_ppp.c:501
 __sock_release+0xcd/0x2b0 net/socket.c:602
 sock_close+0x15/0x20 net/socket.c:1139
 __fput+0x25f/0x790 fs/file_table.c:210
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1d6/0x220 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4163e1
RSP: 002b:00007ffe05850160 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000006 RCX: 00000000004163e1
RDX: 0000000000000000 RSI: 0000000000000081 RDI: 0000000000000005
RBP: 0000000000000000 R08: 00000000007714b8 R09: 01ffffffffffffff
R10: 00007ffe05850230 R11: 0000000000000293 R12: 000000000076bf00
R13: 00000000007714c0 R14: 0000000000000000 R15: 000000000076bf0c
Code: 97 fb 48 8d bb 88 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 d2 00 00 00 4c 8b ab 88 01 00 00 <f0> 41 ff 8d 80 00 00 00 0f 88 03 85 7b 00 74 70 e8 58 af 97 fb 
CPU: 1 PID: 11755 Comm: syz-executor.4 Not tainted 4.14.175-syzkaller #0
RIP: refcount_dec_and_test arch/x86/include/asm/refcount.h:75 [inline] RSP: ffff888202a5fcd0
RIP: sock_put include/net/sock.h:1657 [inline] RSP: ffff888202a5fcd0
RIP: l2tp_session_free+0x113/0x200 net/l2tp/l2tp_core.c:1714 RSP: ffff888202a5fcd0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
CR2: 0000000000000080
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x13e/0x194 lib/dump_stack.c:58
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold+0x10a/0x14b lib/fault-inject.c:149
 should_failslab+0xd6/0x130 mm/failslab.c:32
 slab_pre_alloc_hook mm/slab.h:421 [inline]
 slab_alloc mm/slab.c:3376 [inline]
 kmem_cache_alloc_trace+0x2db/0x7b0 mm/slab.c:3616
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 assoc_array_insert_in_empty_tree lib/assoc_array.c:474 [inline]
 assoc_array_insert+0x6ec/0x2cf0 lib/assoc_array.c:1009
 __key_link_begin+0x106/0x2b0 security/keys/keyring.c:1238
 key_link+0x70/0x230 security/keys/keyring.c:1371
 key_get_persistent security/keys/persistent.c:116 [inline]
 keyctl_get_persistent+0x4df/0x790 security/keys/persistent.c:164
 SYSC_keyctl security/keys/keyctl.c:1739 [inline]
 SyS_keyctl+0x98/0x2a2 security/keys/keyctl.c:1638
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007f8e1f069c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000fa
RAX: ffffffffffffffda RBX: 00007f8e1f06a6d4 RCX: 000000000045c849
RDX: 000000002a0d97c1 RSI: 0000000000000000 RDI: 0000000000000016
---[ end trace da323c55b40dd661 ]---
RBP: 000000000076bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
R13: 00000000000006fb R14: 00000000004c9c91 R15: 0000000000000001