WARNING: proc registration bug in _

 build_skb+0x6f/0x2a0 net/core/skbuff.c:312
 tun_build_skb.isra.50+0x9cb/0x1810 drivers/net/tun.c:1690
proc_dir_entry 'ipt_CLUSTERIP/172.20.7.170' already registered
WARNING: CPU: 0 PID: 6092 at fs/proc/generic.c:330 proc_register+0x2a4/0x370 fs/proc/generic.c:329
Kernel panic - not syncing: panic_on_warn set ...

 tun_get_user+0x17d0/0x3940 drivers/net/tun.c:1800
 tun_chr_write_iter+0xb9/0x160 drivers/net/tun.c:1986
 call_write_iter include/linux/fs.h:1781 [inline]
 do_iter_readv_writev+0x55c/0x830 fs/read_write.c:653
 do_iter_write+0x154/0x540 fs/read_write.c:932
 vfs_writev+0x18a/0x340 fs/read_write.c:977
 do_writev+0xfc/0x2a0 fs/read_write.c:1012
 SYSC_writev fs/read_write.c:1085 [inline]
 SyS_writev+0x27/0x30 fs/read_write.c:1082
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x453931
RSP: 002b:00007f82f857dba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007f82f857da90 RCX: 0000000000453931
RDX: 0000000000000001 RSI: 00007f82f857dbf0 RDI: 0000000000000012
RBP: 00007f82f857da80 R08: 0000000000000012 R09: 0000000000000000
R10: 0000000000000066 R11: 0000000000000293 R12: 00000000004b8925
R13: 00007f82f857dbb8 R14: 00000000004b8925 R15: 0000000000000000
CPU: 0 PID: 6092 Comm: syz-executor7 Not tainted 4.15.0+ #221
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+0x194/0x257 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+0x22/0x40 arch/x86/entry/entry_64.S:1097
RIP: 0010:proc_register+0x2a4/0x370 fs/proc/generic.c:329
RSP: 0018:ffff8801b3def528 EFLAGS: 00010286
RAX: dffffc0000000008 RBX: ffff8801ae7c0af8 RCX: ffffffff815a57ae
RDX: 0000000000010000 RSI: ffffc900019b2000 RDI: 1ffff100367bde2a
RBP: ffff8801b3def578 R08: 1ffff100367bddec R09: 0000000000000000
R10: ffff8801b3def3e0 R11: 0000000000000000 R12: ffff8801b3e0e0c0
R13: dffffc0000000000 R14: ffff8801cb8ce488 R15: ffff8801b3e0e181
 proc_create_data+0xf8/0x180 fs/proc/generic.c:494
 clusterip_config_init net/ipv4/netfilter/ipt_CLUSTERIP.c:250 [inline]
 clusterip_tg_check+0xf9c/0x16d0 net/ipv4/netfilter/ipt_CLUSTERIP.c:488
 xt_check_target+0x22c/0x7d0 net/netfilter/x_tables.c:850
 check_target net/ipv4/netfilter/ip_tables.c:513 [inline]
 find_check_entry.isra.8+0x8c8/0xcb0 net/ipv4/netfilter/ip_tables.c:554
 translate_table+0xed1/0x1610 net/ipv4/netfilter/ip_tables.c:725
 do_replace net/ipv4/netfilter/ip_tables.c:1141 [inline]
 do_ipt_set_ctl+0x370/0x5f0 net/ipv4/netfilter/ip_tables.c:1675
 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
 nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
 ip_setsockopt+0x97/0xa0 net/ipv4/ip_sockglue.c:1259
 udp_setsockopt+0x45/0x80 net/ipv4/udp.c:2401
 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2975
 SYSC_setsockopt net/socket.c:1849 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1828
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x453a59
RSP: 002b:00007fac657c6c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007fac657c76d4 RCX: 0000000000453a59
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000014
RBP: 000000000071bf58 R08: 0000000000000360 R09: 0000000000000000
R10: 0000000020664ca0 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000128 R14: 00000000006f1c60 R15: 0000000000000001
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..