linux-kernel - Re: [PATCHv2 net] usbnet: modern method to get random MAC

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Message-ID: <93a8a951-7e0f-4504-8407-15d920236f9c@suse.com>
Date: Tue, 15 Oct 2024 09:48:56 +0200
From: Oliver Neukum <oneukum@...e.com>
To: Eric Dumazet <edumazet@...gle.com>, Oliver Neukum <oneukum@...e.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
 netdev@...r.kernel.org, linux-usb@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...nel.org,
 John Sperbeck <jsperbeck@...gle.com>, Brian Vazquez <brianvv@...gle.com>
Subject: Re: [PATCHv2 net] usbnet: modern method to get random MAC



On 15.10.24 01:00, Eric Dumazet wrote:
> On Tue, Oct 15, 2024 at 12:24 AM Oliver Neukum <oneukum@...e.com> wrote:
>>
>> On 14.10.24 21:59, Eric Dumazet wrote:
>>
>>> As diagnosed by John Sperbeck :
>>>
>>> This patch implies all ->bind() method took care of populating net->dev_addr ?
>>>
>>> Otherwise the following existing heuristic is no longer working
>>>
>>> // heuristic:  "usb%d" for links we know are two-host,
>>> // else "eth%d" when there's reasonable doubt.  userspace
>>> // can rename the link if it knows better.
>>> if ((dev->driver_info->flags & FLAG_ETHER) != 0 &&
>>>       ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 ||
>>>        (net->dev_addr [0] & 0x02) == 0))
>>> strscpy(net->name, "eth%d", sizeof(net->name));
>>>
>>
>> Hi,
>>
>> you need to have a MAC to be an ethernet device, don't you?
> 
> Before or after your patch, there was/is a MAC address, eventually random.
> 
> The problem is about the test, which is now done while dev->dev_addr
> is full of zeroes, which is not a valid address,
> as shown by :

Hi,

I am sorry I misunderstood you. Yes, I overlooked the test for whether
the MAC has been altered. I am preparing a patch. Could you give me
John Perbeck's address, so I can include him in "reported-by"?

	Sorry
		Oliver