ipvs: ignore IP_VS_SVC_F_HASHED flag when adding service

syzbot reported memory leak [1] when adding service with
HASHED flag. We should ignore this flag both from sockopt
and netlink provided data, otherwise the service is not
hashed and not visible while releasing resources.

[1]
BUG: memory leak
unreferenced object 0xffff888115227800 (size 512):
  comm "syz-executor263", pid 8658, jiffies 4294951882 (age 12.560s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff83977188>] kmalloc include/linux/slab.h:556 [inline]
    [<ffffffff83977188>] kzalloc include/linux/slab.h:686 [inline]
    [<ffffffff83977188>] ip_vs_add_service+0x598/0x7c0 net/netfilter/ipvs/ip_vs_ctl.c:1343
    [<ffffffff8397d770>] do_ip_vs_set_ctl+0x810/0xa40 net/netfilter/ipvs/ip_vs_ctl.c:2570
    [<ffffffff838449a8>] nf_setsockopt+0x68/0xa0 net/netfilter/nf_sockopt.c:101
    [<ffffffff839ae4e9>] ip_setsockopt+0x259/0x1ff0 net/ipv4/ip_sockglue.c:1435
    [<ffffffff839fa03c>] raw_setsockopt+0x18c/0x1b0 net/ipv4/raw.c:857
    [<ffffffff83691f20>] __sys_setsockopt+0x1b0/0x360 net/socket.c:2117
    [<ffffffff836920f2>] __do_sys_setsockopt net/socket.c:2128 [inline]
    [<ffffffff836920f2>] __se_sys_setsockopt net/socket.c:2125 [inline]
    [<ffffffff836920f2>] __x64_sys_setsockopt+0x22/0x30 net/socket.c:2125
    [<ffffffff84350efa>] do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
    [<ffffffff84400068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported-and-tested-by: syzbot+e562383183e4b1766930@syzkaller.appspotmail.com
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Reviewed-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/ipvs/ip_vs_ctl.c

@@ -1367,7 +1367,7 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u,
 	ip_vs_addr_copy(svc->af, &svc->addr, &u->addr);
 	svc->port = u->port;
 	svc->fwmark = u->fwmark;
-	svc->flags = u->flags;
+	svc->flags = u->flags & ~IP_VS_SVC_F_HASHED;
 	svc->timeout = u->timeout * HZ;
 	svc->netmask = u->netmask;
 	svc->ipvs = ipvs;