netdev - [PATCH] ip6_gre: reload ipv6h in prepare_ip6gre_xmit

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Date:   Wed, 24 Jul 2019 20:00:42 +0800
From:   Haishuang Yan <yanhaishuang@...s.chinamobile.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Haishuang Yan <yanhaishuang@...s.chinamobile.com>,
        William Tu <u9012063@...il.com>
Subject: [PATCH] ip6_gre: reload ipv6h in prepare_ip6gre_xmit_ipv6

Since ip6_tnl_parse_tlv_enc_lim() can call pskb_may_pull()
which may change skb->data, so we need to re-load ipv6h at
the right place.

Fixes: 898b29798e36 ("ip6_gre: Refactor ip6gre xmit codes")
Cc: William Tu <u9012063@...il.com>
Signed-off-by: Haishuang Yan <yanhaishuang@...s.chinamobile.com>
---
 net/ipv6/ip6_gre.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index c2049c7..dd2d0b96 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -660,12 +660,13 @@ static int prepare_ip6gre_xmit_ipv6(struct sk_buff *skb,
 				    struct flowi6 *fl6, __u8 *dsfield,
 				    int *encap_limit)
 {
-	struct ipv6hdr *ipv6h = ipv6_hdr(skb);
+	struct ipv6hdr *ipv6h;
 	struct ip6_tnl *t = netdev_priv(dev);
 	__u16 offset;
 
 	offset = ip6_tnl_parse_tlv_enc_lim(skb, skb_network_header(skb));
 	/* ip6_tnl_parse_tlv_enc_lim() might have reallocated skb->head */
+	ipv6h = ipv6_hdr(skb);
 
 	if (offset > 0) {
 		struct ipv6_tlv_tnl_enc_lim *tel;
-- 
1.8.3.1