linux-kernel - Re: [PATCH 1/2 v2] usbnet: fix bad header length bug

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Message-ID: <87iosn86en.fsf@nemi.mork.no>
Date:	Mon, 10 Feb 2014 14:05:20 +0100
From:	Bjørn Mork <bjorn@...k.no>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	Emil Goode <emilgoode@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Ming Lei <ming.lei@...onical.com>,
	Mark Brown <broonie@...aro.org>,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
	Glen Turner <gdt@....id.au>, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2 v2] usbnet: fix bad header length bug

Oliver Neukum <oliver@...kum.org> writes:
> On Mon, 2014-02-10 at 13:00 +0100, Emil Goode wrote:
>> On Mon, Feb 10, 2014 at 07:40:58AM +0100, Oliver Neukum wrote:
>
>> > Well, then how about simply removing the check?
>> > It seems to have outlived its usefulness.
>> > 
>> > 	Regards
>> > 		Oliver
>> > 
>> >
>> 
>> I did consider that and I think it is probably the best thing to do.
>> However, I think the removal of the check could have negative effects
>> on the other minidrivers, at least the qmi_wwan minidriver explicitly
>> states that it is depending on this check to be made in rx_complete().
>
> <censored>.

No need to do that.  I had the exact same reaction myself :-)

Anyway, I put that comment there mostly as a note to myself why the
check would be redundant at that point.  I don't see any problem with
removing the generic check in usbnet as long as we add similar checks
whereever they are needed, like in qmi_wwan.

Note that usbnet_skb_return will be one of those places.  It calls
eth_type_trans() on the skb, so it should verify that the length is at
least ETH_HLEN first.

> Oh well. But how about merging it with FLAG_MULTI_PACKET?
> I really don't want to add more flags. There is a point where enough
> flags make absurd having a common code. We are closing in on that point.

Agreed.  I would even say we are past that point...


Bjørn
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