------------[ cut here ]------------
tunl0: caps=(0x00000000401d7869, 0x00000000401d7869) len=2719 data_len=2639 gso_size=1428 gso_type=1 ip_summed=3
WARNING: CPU: 1 PID: 15287 at net/core/dev.c:2635 skb_warn_bad_offload+0x2c9/0x3d0 net/core/dev.c:2630
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 15287 Comm: syz-executor3 Not tainted 4.16.0-rc2+ #248
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 panic+0x1e4/0x41c kernel/panic.c:183
 __warn+0x1dc/0x200 kernel/panic.c:547
 report_bug+0x211/0x2d0 lib/bug.c:184
 fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
 fixup_bug arch/x86/kernel/traps.c:247 [inline]
 do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x58/0x80 arch/x86/entry/entry_64.S:957
RIP: 0010:skb_warn_bad_offload+0x2c9/0x3d0 net/core/dev.c:2630
RSP: 0018:ffff8801d35aec78 EFLAGS: 00010282
RAX: dffffc0000000008 RBX: ffff8801a9e0e000 RCX: ffffffff815ac30e
RDX: 0000000000010000 RSI: ffffc90001fa3000 RDI: 1ffff1003a6b5d14
RBP: ffff8801d35aecd0 R08: 1ffff1003a6b5cd6 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000003
R13: ffff8801a9e0e000 R14: ffff8801bb134da0 R15: 0000000000000001
 skb_checksum_help+0x7c4/0xb60 net/core/dev.c:2651
 checksum_tg+0x59/0x70 net/netfilter/xt_CHECKSUM.c:29
 ipt_do_table+0xd05/0x19b0 net/ipv4/netfilter/ip_tables.c:348
 iptable_mangle_hook+0xa7/0x4a0 net/ipv4/netfilter/iptable_mangle.c:85
 nf_hook_entry_hookfn include/linux/netfilter.h:120 [inline]
 nf_hook_slow+0xba/0x1a0 net/netfilter/core.c:483
 nf_hook include/linux/netfilter.h:243 [inline]
 NF_HOOK_COND include/linux/netfilter.h:275 [inline]
 ip_output+0x5c4/0x860 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:443 [inline]
 ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124
 ip_queue_xmit+0x8c0/0x18e0 net/ipv4/ip_output.c:504
 tcp_transmit_skb+0x1b12/0x3960 net/ipv4/tcp_output.c:1176
 tcp_write_xmit+0x882/0x5430 net/ipv4/tcp_output.c:2373
 __tcp_push_pending_frames+0xa0/0x250 net/ipv4/tcp_output.c:2546
 tcp_send_fin+0x1b0/0xd20 net/ipv4/tcp_output.c:3088
 tcp_close+0xcd9/0x1190 net/ipv4/tcp.c:2231
 inet_release+0xed/0x1c0 net/ipv4/af_inet.c:427
 sock_release+0x8d/0x1e0 net/socket.c:594
 sock_close+0x16/0x20 net/socket.c:1149
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x6e5/0x940 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x453d69
RSP: 002b:00007f0f0d9cbc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f0f0d9cc6d4 RCX: 0000000000453d69
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000052 R14: 00000000006f0850 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..