netdev - [PATCH] ipv6: fix useless rol32 call on hash

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Message-Id: <20180717161239.30782-1-colin.king@canonical.com>
Date:   Tue, 17 Jul 2018 17:12:39 +0100
From:   Colin King <colin.king@...onical.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ipv6: fix useless rol32 call on hash

From: Colin Ian King <colin.king@...onical.com>

The rol32 call is currently rotating hash but the rol'd value is
being discarded. I believe the current code is incorrect and hash
should be assigned the rotated value returned from rol32.

Thanks to David Lebrun for spotting this.

Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 include/net/ipv6.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 50eebccbf919..190015652168 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -843,7 +843,7 @@ static inline __be32 ip6_make_flowlabel(struct net *net, struct sk_buff *skb,
 	 * to minimize possbility that any useful information to an
 	 * attacker is leaked. Only lower 20 bits are relevant.
 	 */
-	rol32(hash, 16);
+	hash = rol32(hash, 16);
 
 	flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
 
-- 
2.17.1