netdev - Re: [PATCH V2 net] net: fix tcp reset packet flowlabel for ipv6

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Date:   Mon, 24 Jul 2017 16:12:53 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     Shaohua Li <shli@...nel.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        kernel-team <Kernel-team@...com>, Shaohua Li <shli@...com>,
        Eric Dumazet <eric.dumazet@...il.com>, flo@...rcot.fr
Subject: Re: [PATCH V2 net] net: fix tcp reset packet flowlabel for ipv6

On Mon, Jul 24, 2017 at 1:34 PM, David Miller <davem@...emloft.net> wrote:
> From: Shaohua Li <shli@...nel.org>
> Date: Tue, 18 Jul 2017 12:03:37 -0700
>
>> +     /* Since this is being sent on the wire obfuscate hash a bit
>> +      * to minimize possbility that any useful information to an
>> +      * attacker is leaked. Only lower 20 bits are relevant.
>> +      */
>> +     rol32(hash, 16);
>
> This doesn't help anything at all.

I believe the above code is copy-n-pasted from ip6_make_flowlabel()
(with few adjustments). Don't know why we can't refactor that function
for reuse.