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Subject: Re: [PATCH 3/3] nl80211: Include wiphy address setup in NEW_WIPHY
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     linux-wireless@vger.kernel.org
References: <20190619223606.4575-1-denkenz@gmail.com>
 <20190619223606.4575-3-denkenz@gmail.com>
 <ec1ca95a5789f9001e89e603633b20316d687721.camel@sipsolutions.net>
From:   Denis Kenzior <denkenz@gmail.com>
Message-ID: <7da9b924-78c7-ba72-fecc-a11700a34ff4@gmail.com>
Date:   Thu, 20 Jun 2019 11:16:33 -0500
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Hi Johannes,

On 06/20/2019 01:58 AM, Johannes Berg wrote:
> Didn't really review all of this yet, but
> 
>   	switch (state->split_start) {
>>   	case 0:
>> +		if (nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN,
>> +			    rdev->wiphy.perm_addr))
>> +			goto nla_put_failure;
> 
> We generally can't add anything to any of the cases before the split was
> allowed, for compatibility with old userspace.

Can you educate me here? Is it because the non-split dump messages would 
grow too large?  But then non-dumps aren't split, so I still don't get 
how anyone can be broken by this (that isn't already broken in the first 
place).

Anyhow, What is the cut off point?  It didn't seem worthwhile to send 
yet-another-message for ~60 bytes of data, but if you want me to add it 
as a separate message, no problem.

Regards,
-Denis