------------[ cut here ]------------
WARNING: CPU: 0 PID: 13122 at net/ipv4/route.c:1270 ip_rt_bug+0x2b/0x120 net/ipv4/route.c:1270
Modules linked in:
CPU: 0 UID: 0 PID: 13122 Comm: syz.7.2018 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:ip_rt_bug+0x2b/0x120 net/ipv4/route.c:1270
Code: 0f 1e fa 41 54 55 53 48 89 d3 48 83 ec 08 e8 fc 9d f8 f7 66 90 e8 f5 9d f8 f7 ba 02 00 00 00 48 89 de 31 ff e8 46 b0 6e ff 90 <0f> 0b 90 48 83 c4 08 31 c0 5b 5d 41 5c e9 c3 8c a4 01 e8 ce 9d f8
RSP: 0018:ffffc900235ef3b8 EFLAGS: 00010293

RAX: 0000000000000000 RBX: ffff888049938000 RCX: 0000000000000002
RDX: ffff888035112480 RSI: ffffffff89c49aca RDI: ffffffff8bf1e3c0
RBP: ffff888049938000 R08: 0000000000000001 R09: 0000000000000001
R10: ffffc900235ef368 R11: 0000000000000001 R12: ffff88805459a480
R13: ffff888100b57800 R14: ffff8880605f4a00 R15: ffff888049938058
FS:  00007f1b748726c0(0000) GS:ffff8880d69d9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1b74871f98 CR3: 000000005d597000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 dst_output include/net/dst.h:464 [inline]
 dst_output include/net/dst.h:462 [inline]
 ip_local_out net/ipv4/ip_output.c:131 [inline]
 ip_send_skb net/ipv4/ip_output.c:1508 [inline]
 ip_push_pending_frames+0x419/0x5d0 net/ipv4/ip_output.c:1528
 icmp_push_reply+0x308/0x440 net/ipv4/icmp.c:395
 __icmp_send+0xce3/0x19c0 net/ipv4/icmp.c:787
 icmp_send include/net/icmp.h:43 [inline]
 ip_options_compile+0xb6/0x100 net/ipv4/ip_options.c:473
 ip_rcv_options net/ipv4/ip_input.c:288 [inline]
 ip_rcv_finish_core+0x6de/0x2290 net/ipv4/ip_input.c:391
 ip_rcv_finish net/ipv4/ip_input.c:451 [inline]
 NF_HOOK include/linux/netfilter.h:318 [inline]
 NF_HOOK include/linux/netfilter.h:312 [inline]
 ip_rcv+0x1c0/0x600 net/ipv4/ip_input.c:573
 __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:6079
 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6192
 netif_receive_skb_internal net/core/dev.c:6278 [inline]
 netif_receive_skb+0x137/0x7b0 net/core/dev.c:6337
 tun_rx_batched.isra.0+0x3ee/0x740 drivers/net/tun.c:1509
 tun_get_user+0x28b2/0x3cc0 drivers/net/tun.c:1953
 tun_chr_write_iter+0xdc/0x210 drivers/net/tun.c:1999
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x7d3/0x11d0 fs/read_write.c:686
 ksys_write+0x12a/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1b7398d97f
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007f1b74872000 EFLAGS: 00000293
 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1b73be5fa0 RCX: 00007f1b7398d97f
RDX: 0000000000000046 RSI: 0000200000000400 RDI: 00000000000000c8