syzbot

 netlink_ack+0x514/0x9a0 net/netlink/af_netlink.c:2403
 nfnl_err_deliver net/netfilter/nfnetlink.c:270 [inline]
 nfnetlink_rcv_batch net/netfilter/nfnetlink.c:451 [inline]
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:495 [inline]
 nfnetlink_rcv+0x147b/0x1da0 net/netfilter/nfnetlink.c:513
: caps=(0x0000000000000000, 0x00000144401d7c69) len=284 data_len=0 gso_size=116 gso_type=1 ip_summed=3
 netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
 netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1313
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7 at net/core/dev.c:2609 skb_warn_bad_offload.cold+0x1d1/0x44d net/core/dev.c:2609
Kernel panic - not syncing: panic_on_warn set ...

 netlink_sendmsg+0x62e/0xb80 net/netlink/af_netlink.c:1878
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 ___sys_sendmsg+0x6c8/0x800 net/socket.c:2062
 __sys_sendmsg+0xa3/0x120 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x27/0x40 net/socket.c:2103
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45e149
RSP: 002b:00007fb601695c68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 000000000045e149
RDX: 0000000000000000 RSI: 000000002000c2c0 RDI: 0000000000000003
RBP: 00007fb601695ca0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
R13: 00007ffda1bfec5f R14: 00007fb6016969c0 R15: 000000000119bf8c
CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 4.14.212-syzkaller #0
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+0x1b2/0x283 lib/dump_stack.c:58
 panic+0x1f9/0x42d kernel/panic.c:183
 __warn.cold+0x20/0x4b kernel/panic.c:547
 report_bug+0x208/0x249 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 fixup_bug arch/x86/kernel/traps.c:172 [inline]
 do_error_trap+0x195/0x2d0 arch/x86/kernel/traps.c:295
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964
RIP: 0010:skb_warn_bad_offload.cold+0x1d1/0x44d net/core/dev.c:2609
RSP: 0018:ffff8880b540efb0 EFLAGS: 00010286
RAX: 0000000000000066 RBX: ffff888099abb828 RCX: 0000000000000000
RDX: 0000000000000100 RSI: ffffffff878bbac0 RDI: ffffed1016a81dec
RBP: ffffffff88559320 R08: 0000000000000066 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff88557080
R13: 0000000000000074 R14: 0000000000000000 R15: 000000000000011c
 skb_checksum_help+0x627/0x7d0 net/core/dev.c:2630
 checksum_tg+0x52/0x65 net/netfilter/xt_CHECKSUM.c:29
 ipt_do_table+0xa9a/0x16f0 net/ipv4/netfilter/ip_tables.c:353
 ipt_mangle_out net/ipv4/netfilter/iptable_mangle.c:64 [inline]
 iptable_mangle_hook+0x2d5/0x560 net/ipv4/netfilter/iptable_mangle.c:89
 nf_hook_entry_hookfn include/linux/netfilter.h:108 [inline]
 nf_hook_slow+0xb0/0x1a0 net/netfilter/core.c:467
 nf_hook include/linux/netfilter.h:205 [inline]
 __ip_local_out+0x398/0x730 net/ipv4/ip_output.c:114
 ip_local_out+0x25/0x170 net/ipv4/ip_output.c:123
 ip_queue_xmit+0x7d3/0x1a80 net/ipv4/ip_output.c:505
 __tcp_transmit_skb+0x17e2/0x2cb0 net/ipv4/tcp_output.c:1133
 tcp_transmit_skb net/ipv4/tcp_output.c:1149 [inline]
 tcp_write_xmit+0x69d/0x4e10 net/ipv4/tcp_output.c:2393
 __tcp_push_pending_frames+0xa0/0x2d0 net/ipv4/tcp_output.c:2577
 tcp_push_pending_frames include/net/tcp.h:1778 [inline]
 tcp_data_snd_check net/ipv4/tcp_input.c:5132 [inline]
 tcp_rcv_state_process+0xca9/0x494e net/ipv4/tcp_input.c:6175
 tcp_v4_do_rcv+0x2c4/0x7d0 net/ipv4/tcp_ipv4.c:1498
 tcp_v4_rcv+0x275c/0x3560 net/ipv4/tcp_ipv4.c:1750
 ip_local_deliver_finish+0x3f2/0xab0 net/ipv4/ip_input.c:216
 NF_HOOK include/linux/netfilter.h:250 [inline]
 ip_local_deliver+0x167/0x460 net/ipv4/ip_input.c:257
 dst_input include/net/dst.h:476 [inline]
 ip_rcv_finish+0x6e3/0x19f0 net/ipv4/ip_input.c:396
 NF_HOOK include/linux/netfilter.h:250 [inline]
 ip_rcv+0x8a7/0xf01 net/ipv4/ip_input.c:493
 __netif_receive_skb_core+0x15ee/0x2a30 net/core/dev.c:4474
 __netif_receive_skb+0x27/0x1a0 net/core/dev.c:4512
 process_backlog+0x218/0x6f0 net/core/dev.c:5194
 napi_poll net/core/dev.c:5596 [inline]
 net_rx_action+0x466/0xfd0 net/core/dev.c:5662
 __do_softirq+0x254/0xa1d kernel/softirq.c:288
 run_ksoftirqd+0x50/0x1a0 kernel/softirq.c:670
 smpboot_thread_fn+0x5c1/0x920 kernel/smpboot.c:164
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Kernel Offset: disabled
Rebooting in 86400 seconds..