[PATCH] ipv6: fix useless rol32 call on hash

[PATCH] ipv6: fix useless rol32 call on hash

[Colin King]

From: Colin Ian King <colin.king@canonical.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@canonical.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

Re: [PATCH] ipv6: fix useless rol32 call on hash

[David Miller]

From: Colin King <colin.king@canonical.com>
Date: Tue, 17 Jul 2018 17:12:39 +0100

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

Also applied and queued up for -stable, thanks.