kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 18563 Comm: syz-executor4 Not tainted 4.9.124-g09eb2ba #35
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d39b9800 task.stack: ffff8801a45d0000
RIP: 0010:[<ffffffff8356164d>]  [<ffffffff8356164d>] ip6_xmit+0xb2d/0x1b80 net/ipv6/ip6_output.c:254
RSP: 0018:ffff8801a45d7738  EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff8801cd2b0500 RCX: ffffc9000d517000
RDX: ffff8801cd2b0578 RSI: ffffffff83561613 RDI: ffff8801c1188318
RBP: ffff8801a45d7950 R08: ffffed00348baf1d R09: ffff8801a45d78a8
R10: ffffed00348baf1c R11: 0000000000000003 R12: ffff8801c41a4480
R13: ffff8801a3cb5de4 R14: 000000000000001b R15: 0000000000000040
FS:  0000000000000000(0000) GS:ffff8801db200000(0063) knlGS:00000000f57b6b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f56e4ffc CR3: 00000001b5c16000 CR4: 00000000001606f0
Stack:
 ffffffff8153f4a2 ffffffff8153c8ab ffffffff8303637b ffffffff8304364f
 0000006d00000001 0000000000000000 1ffff100348baef5 ffff8801cd2b05c8
 ffff8801cd2b0558 ffff8801cd2b0578 ffff8801a5c21380 ffff8801a38199c0
Call Trace:
 [<ffffffff836275ec>] inet6_csk_xmit+0x27c/0x4d0 net/ipv6/inet6_connection_sock.c:178
 [<ffffffff836c42e5>] l2tp_xmit_core net/l2tp/l2tp_core.c:1178 [inline]
 [<ffffffff836c42e5>] l2tp_xmit_skb+0xc45/0xf30 net/l2tp/l2tp_core.c:1273
 [<ffffffff836cf8b0>] pppol2tp_sendmsg+0x4e0/0x790 net/l2tp/l2tp_ppp.c:339
 [<ffffffff8301e0ac>] sock_sendmsg_nosec net/socket.c:648 [inline]
 [<ffffffff8301e0ac>] sock_sendmsg+0xcc/0x110 net/socket.c:658
 [<ffffffff8301e313>] sock_write_iter+0x223/0x3b0 net/socket.c:856
 [<ffffffff81573440>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff81573440>] __vfs_write+0x3e0/0x580 fs/read_write.c:509
 [<ffffffff81577237>] vfs_write+0x187/0x530 fs/read_write.c:557
 [<ffffffff8157b069>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff8157b069>] SyS_write+0xd9/0x1c0 fs/read_write.c:596
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff83a030d0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 55 0e 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 54 24 48 4d 8b a4 24 18 03 00 00 <65> 49 ff 44 24 28 48 c1 ea 03 0f b6 04 02 84 c0 74 08 3c 03 0f 
RIP  [<ffffffff8356164d>] ip6_xmit+0xb2d/0x1b80 net/ipv6/ip6_output.c:254
 RSP <ffff8801a45d7738>
---[ end trace 11335312a11eb7c6 ]---