netdev - Question about inet_rtm_getroute_build

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Date:   Thu, 26 Aug 2021 18:16:56 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Roopa Prabhu <roopa@...ulusnetworks.com>,
        Networking <netdev@...r.kernel.org>
Subject: Question about inet_rtm_getroute_build_skb()

Hi Roopa

I noticed inet_rtm_getroute_build_skb() has this endian issue 
when building an UDP header.

Would the following fix break user space ?

Thanks.

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index a6f20ee3533554b210d27c4ab6637ca7a05b148b..50133b935f868c2ae9474eea027a0ad864a43936 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -3170,7 +3170,7 @@ 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;
        }