ipv4: fix endianness issue in inet_rtm_getroute_build_skb()

stable inclusion
from stable-5.10.65
commit c4f1ad3930261ee153b5a1230662fdfb54725e1a
bugzilla: 182361 https://gitee.com/openeuler/kernel/issues/I4EH3U

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c4f1ad3930261ee153b5a1230662fdfb54725e1a

--------------------------------

[ Upstream commit 92548b0e ]

The UDP length field should be in network order.
This removes the following sparse error:

net/ipv4/route.c:3173:27: warning: incorrect type in assignment (different base types)
net/ipv4/route.c:3173:27:    expected restricted __be16 [usertype] len
net/ipv4/route.c:3173:27:    got unsigned long

Fixes: 404eb77e ("ipv4: support sport, dport and ip_proto in RTM_GETROUTE")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Roopa Prabhu <roopa@nvidia.com>
Cc: David Ahern <dsahern@kernel.org>
Reviewed-by: NDavid Ahern <dsahern@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/ipv4/route.c

@@ -3078,7 +3078,7 @@ static struct sk_buff *inet_rtm_getroute_build_skb(__be32 src, __be32 dst,
 		udph = skb_put_zero(skb, sizeof(struct udphdr));
 		udph->source = sport;
 		udph->dest = dport;
-		udph->len = sizeof(struct udphdr);
+		udph->len = htons(sizeof(struct udphdr));
 		udph->check = 0;
 		break;
 	}