netdev - [PATCH net] ipvs: get sctphdr by sctphoff in sctp_csum

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Message-Id: <cd1c829cfd9ee916e57c51f6879947f0f88c1eb1.1551094063.git.lucien.xin@gmail.com>
Date:   Mon, 25 Feb 2019 19:27:43 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>,
        netfilter-devel@...r.kernel.org
Cc:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>, pablo@...filter.org
Subject: [PATCH net] ipvs: get sctphdr by sctphoff in sctp_csum_check

sctp_csum_check() is called by sctp_s/dnat_handler() where it calls
skb_make_writable() to ensure sctphdr to be linearized.

So there's no need to get sctphdr by calling skb_header_pointer()
in sctp_csum_check().

Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/netfilter/ipvs/ip_vs_proto_sctp.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c
index b0cd7d0..0ecf241 100644
--- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
+++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
@@ -183,7 +183,7 @@ static int
 sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
 {
 	unsigned int sctphoff;
-	struct sctphdr *sh, _sctph;
+	struct sctphdr *sh;
 	__le32 cmp, val;
 
 #ifdef CONFIG_IP_VS_IPV6
@@ -193,10 +193,7 @@ sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
 #endif
 		sctphoff = ip_hdrlen(skb);
 
-	sh = skb_header_pointer(skb, sctphoff, sizeof(_sctph), &_sctph);
-	if (sh == NULL)
-		return 0;
-
+	sh = (struct sctphdr *)(skb->data + sctphoff);
 	cmp = sh->checksum;
 	val = sctp_compute_cksum(skb, sctphoff);
 
-- 
2.1.0