netdev - Re: [PATCH net] geneve: maximum value of VNI cannot be used

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Date:   Thu, 10 Aug 2017 08:58:58 -0700
From:   Girish Moodalbail <girish.moodalbail@...cle.com>
To:     David Miller <davem@...emloft.net>
Cc:     pshelar@....org, netdev@...r.kernel.org
Subject: Re: [PATCH net] geneve: maximum value of VNI cannot be used

On 8/9/17 10:41 PM, David Miller wrote:
> From: Girish Moodalbail <girish.moodalbail@...cle.com>
> Date: Tue,  8 Aug 2017 17:26:24 -0700
> 
>> Geneve's Virtual Network Identifier (VNI) is 24 bit long, so the range
>> of values for it would be from 0 to 16777215 (2^24 -1).  However, one
>> cannot create a geneve device with VNI set to 16777215. This patch fixes
>> this issue.
>>
>> Signed-off-by: Girish Moodalbail <girish.moodalbail@...cle.com>
> 
> I always worry that someone, somewhere, might be using this in some
> way and this will break things.
> 
> But I'll apply this for now.
> 
Thanks David. As per the output of 'ip link help geneve', 16777215 is a valid 
value. However, due to incorrect check in the kernel that value was not supported.

$ ip link help geneve |egrep -A1 VNI
Usage: ... geneve id VNI
                   remote ADDR
--
Where: VNI   := 0-16777215
        ADDR  := IP_ADDRESS

So, this is an off-by-one bug and no one had tripped over it until now.

regards,
~Girish