kernel BUG at net/core/dev.c:LINE!

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 4520f06b Linux 4.14.175
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13dab25de00000
kernel config: https://syzkaller.appspot.com/x/.config?x=93cf891381c0c347
dashboard link: https://syzkaller.appspot.com/bug?extid=7010af67ced6105e5ab6
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=155fbc2be00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11bb17dbe00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7010af...@syzkaller.appspotmail.com

ip_tables: iptables: counters copy to user failed while replacing table
------------[ cut here ]------------
kernel BUG at net/core/dev.c:2648!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 6341 Comm: syz-executor763 Not tainted 4.14.175-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880846780c0 task.stack: ffff888097cd8000
RIP: 0010:skb_checksum_help+0x5fd/0x830 net/core/dev.c:2648
RSP: 0018:ffff888097cdf468 EFLAGS: 00010297
RAX: ffff8880846780c0 RBX: 00000000000000e0 RCX: 0000000000000120
RDX: 0000000000000000 RSI: 000000000000001c RDI: 0000000000000000
RBP: ffff88809dd2cb40 R08: ffff88809dd2cbc0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809dd2cbc4
R13: ffff88809dd2cc0c R14: ffff88809dd2cbd0 R15: 0000000000000000
FS: 0000000000f03880(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000008d0ca000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
checksum_tg+0x52/0x65 net/netfilter/xt_CHECKSUM.c:29
ipt_do_table+0xaaf/0x16d0 net/ipv4/netfilter/ip_tables.c:353
iptable_mangle_hook+0x9c/0x560 net/ipv4/netfilter/iptable_mangle.c:90
nf_hook_entry_hookfn include/linux/netfilter.h:108 [inline]
nf_hook_slow+0xa5/0x1a0 net/netfilter/core.c:467
nf_hook include/linux/netfilter.h:205 [inline]
NF_HOOK include/linux/netfilter.h:248 [inline]
ip_rcv+0xb9e/0xfec net/ipv4/ip_input.c:493
__netif_receive_skb_core+0x1e50/0x2c00 net/core/dev.c:4477
__netif_receive_skb+0x27/0x1a0 net/core/dev.c:4515
netif_receive_skb_internal+0xd7/0x580 net/core/dev.c:4588
tun_rx_batched.isra.0+0x46c/0x7a0 drivers/net/tun.c:1221
tun_get_user+0xcde/0x3880 drivers/net/tun.c:1581
tun_chr_write_iter+0xcf/0x179 drivers/net/tun.c:1608
call_write_iter include/linux/fs.h:1778 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x44e/0x630 fs/read_write.c:482
vfs_write+0x192/0x4e0 fs/read_write.c:544
SYSC_write fs/read_write.c:590 [inline]
SyS_write+0xf2/0x210 fs/read_write.c:582
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441729
RSP: 002b:00007fffbaae6ae8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441729
RDX: 000000000000fdef RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 656c6c616b7a7973 R08: 0000000000001c00 R09: 0000000000402fb0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402fb0
R13: 0000000000403040 R14: 0000000000000000 R15: 0000000000000000
Code: 8b 7c 24 28 e8 75 e0 85 fc e9 0d fe ff ff e8 4b 8e 5c fc 48 89 ef 41 bc ea ff ff ff e8 9d b3 ff ff e9 94 fe ff ff e8 33 8e 5c fc <0f> 0b e8 2c 8e 5c fc 0f 0b e8 25 8e 5c fc 48 8b 54 24 28 48 b8
RIP: skb_checksum_help+0x5fd/0x830 net/core/dev.c:2648 RSP: ffff888097cdf468
---[ end trace dd20dd799c821843 ]---


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