KMSAN: uninit-value in do_ip_vs_set_ctl

KMSAN: uninit-value in do_ip_vs_set_ctl

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    06b2df0593a8 kmsan: unpoison only the created pages in get..
git tree:       https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=11a6ae37800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4ca1e57bafa8ab1f
dashboard link: https://syzkaller.appspot.com/bug?extid=23b5f9e7caf61d9a3898
compiler:       clang version 7.0.0 (trunk 329391)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14008417800000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11deb017800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+23b5f9e7caf61d9a3898@syzkaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
==================================================================
BUG: KMSAN: uninit-value in do_ip_vs_set_ctl+0x15ac/0x2760  
net/netfilter/ipvs/ip_vs_ctl.c:2424
CPU: 1 PID: 4464 Comm: syz-executor844 Not tainted 4.17.0-rc3+ #94
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x185/0x1d0 lib/dump_stack.c:113
  kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1084
  __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
  do_ip_vs_set_ctl+0x15ac/0x2760 net/netfilter/ipvs/ip_vs_ctl.c:2424
  nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
  nf_setsockopt+0x476/0x4d0 net/netfilter/nf_sockopt.c:115
  ip_setsockopt+0x24b/0x2b0 net/ipv4/ip_sockglue.c:1253
  raw_setsockopt+0x2e5/0x350 net/ipv4/raw.c:868
  sock_common_setsockopt+0x136/0x170 net/core/sock.c:3039
  __sys_setsockopt+0x4af/0x560 net/socket.c:1903
  __do_sys_setsockopt net/socket.c:1914 [inline]
  __se_sys_setsockopt net/socket.c:1911 [inline]
  __x64_sys_setsockopt+0x15c/0x1c0 net/socket.c:1911
  do_syscall_64+0x154/0x220 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x43fca9
RSP: 002b:00007fff7a4795b8 EFLAGS: 00000213 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fca9
RDX: 0000000000000480 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000213 R12: 00000000004015d0
R13: 0000000000401660 R14: 0000000000000000 R15: 0000000000000000

Local variable description: ----arg@do_ip_vs_set_ctl
Variable was created at:
  read_pnet include/net/net_namespace.h:288 [inline]
  sock_net include/net/sock.h:2306 [inline]
  do_ip_vs_set_ctl+0x93/0x2760 net/netfilter/ipvs/ip_vs_ctl.c:2347
  nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
  nf_setsockopt+0x476/0x4d0 net/netfilter/nf_sockopt.c:115
==================================================================


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