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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Cong Wang <cong.wang@bytedance.com>,
        Peilin Ye <peilin.ye@bytedance.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 22/86] ip6_gre: Avoid updating tunnel->tun_hlen in __gre6_xmit()
Date:   Tue, 26 Apr 2022 10:20:50 +0200
Message-Id: <20220426081741.851720454@linuxfoundation.org>
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From: Peilin Ye <peilin.ye@bytedance.com>

[ Upstream commit f40c064e933d7787ca7411b699504d7a2664c1f5 ]

Do not update tunnel->tun_hlen in data plane code.  Use a local variable
instead, just like "tunnel_hlen" in net/ipv4/ip_gre.c:gre_fb_xmit().

Co-developed-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ipv6/ip6_gre.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 9a0263f25232..949d6fbc1ca0 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -743,6 +743,7 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
 		struct ip_tunnel_info *tun_info;
 		const struct ip_tunnel_key *key;
 		__be16 flags;
+		int tun_hlen;
 
 		tun_info = skb_tunnel_info_txcheck(skb);
 		if (IS_ERR(tun_info) ||
@@ -760,9 +761,9 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
 		dsfield = key->tos;
 		flags = key->tun_flags &
 			(TUNNEL_CSUM | TUNNEL_KEY | TUNNEL_SEQ);
-		tunnel->tun_hlen = gre_calc_hlen(flags);
+		tun_hlen = gre_calc_hlen(flags);
 
-		gre_build_header(skb, tunnel->tun_hlen,
+		gre_build_header(skb, tun_hlen,
 				 flags, protocol,
 				 tunnel_id_to_key32(tun_info->key.tun_id),
 				 (flags & TUNNEL_SEQ) ? htonl(tunnel->o_seqno++)
-- 
2.35.1