WARNING in ip_rt_bug

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: c10b57a5 Linux 4.14.176
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14da6c20100000
kernel config: https://syzkaller.appspot.com/x/.config?x=457897b554d08537
dashboard link: https://syzkaller.appspot.com/bug?extid=ebf0599539716fed62b3
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15124a00100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14ed2357e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ebf059...@syzkaller.appspotmail.com

syz-executor690 uses obsolete (PF_INET,SOCK_PACKET)
------------[ cut here ]------------
WARNING: CPU: 0 PID: 6314 at net/ipv4/route.c:1244 ip_rt_bug+0x11/0x20 net/ipv4/route.c:1243
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 6314 Comm: syz-executor690 Not tainted 4.14.176-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+0x13e/0x194 lib/dump_stack.c:58
panic+0x1f9/0x42d kernel/panic.c:183
__warn.cold+0x2f/0x30 kernel/panic.c:547
report_bug+0x20a/0x248 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:963
RIP: 0010:ip_rt_bug+0x11/0x20 net/ipv4/route.c:1244
RSP: 0018:ffff88809afa73b8 EFLAGS: 00010297
RAX: ffff888097d70500 RBX: ffffffff886d9b80 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff87d842e0 RDI: 0000000000000282
RBP: ffff88809ef05e80 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809dd592c0
R13: ffff88809ef05e80 R14: ffff8880a66aabc0 R15: ffff88809ef05ed8
dst_output include/net/dst.h:462 [inline]
ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124
ip_send_skb+0x3a/0xc0 net/ipv4/ip_output.c:1422
ip_push_pending_frames+0x5f/0x80 net/ipv4/ip_output.c:1442
icmp_push_reply+0x381/0x4f0 net/ipv4/icmp.c:395
__icmp_send+0x90f/0x1110 net/ipv4/icmp.c:743
icmp_send include/net/icmp.h:47 [inline]
ip_options_compile+0x93/0xc0 net/ipv4/ip_options.c:485
ip_rcv_options net/ipv4/ip_input.c:283 [inline]
ip_rcv_finish+0x657/0x1a10 net/ipv4/ip_input.c:364
NF_HOOK include/linux/netfilter.h:250 [inline]
NF_HOOK include/linux/netfilter.h:244 [inline]
ip_rcv+0x9d8/0xfec 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: 0033:0x440699
RSP: 002b:00007fff0b9f57f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440699
RDX: 000000000000100c RSI: 0000000020000240 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000002c00 R09: 00007fff0000000d
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401f20
R13: 0000000000401fb0 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


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