------------[ cut here ]------------
refcount_t: increment on 0; use-after-free.
WARNING: CPU: 1 PID: 23533 at lib/refcount.c:156 refcount_inc_checked lib/refcount.c:156 [inline]
WARNING: CPU: 1 PID: 23533 at lib/refcount.c:156 refcount_inc_checked+0x61/0x70 lib/refcount.c:154
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 23533 Comm: syz-executor.2 Not tainted 5.1.0-rc7+ #93
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+0x172/0x1f0 lib/dump_stack.c:113
 panic+0x2cb/0x65c kernel/panic.c:214
 __warn.cold+0x20/0x45 kernel/panic.c:571
 report_bug+0x263/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973
RIP: 0010:refcount_inc_checked lib/refcount.c:156 [inline]
RIP: 0010:refcount_inc_checked+0x61/0x70 lib/refcount.c:154
Code: 1d 98 2b 2a 06 31 ff 89 de e8 db 2c 40 fe 84 db 75 dd e8 92 2b 40 fe 48 c7 c7 20 7a a1 87 c6 05 78 2b 2a 06 01 e8 7d d9 12 fe <0f> 0b eb c1 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41
RSP: 0018:ffff888069f0fba8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 000000000000f353 RSI: ffffffff815afcb6 RDI: ffffed100d3e1f67
RBP: ffff888069f0fbb8 R08: ffff88809b1845c0 R09: ffffed1015d23ef1
R10: ffffed1015d23ef0 R11: ffff8880ae91f787 R12: ffff8880a8f26968
R13: 0000000000000004 R14: dffffc0000000000 R15: ffff8880a49a6440
 l2tp_tunnel_inc_refcount net/l2tp/l2tp_core.h:240 [inline]
 l2tp_tunnel_get+0x250/0x580 net/l2tp/l2tp_core.c:173
 pppol2tp_connect+0xc00/0x1c70 net/l2tp/l2tp_ppp.c:702
 __sys_connect+0x266/0x330 net/socket.c:1808
 __do_sys_connect net/socket.c:1819 [inline]
 __se_sys_connect net/socket.c:1816 [inline]
 __x64_sys_connect+0x73/0xb0 net/socket.c:1816
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458da9
Code: ad b8 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f83ffe41c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458da9
RDX: 0000000000000026 RSI: 0000000020000180 RDI: 0000000000000005
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f83ffe426d4
R13: 00000000004bf20b R14: 00000000004d02f0 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..