netdev - Re: [PATCH net] packet: packet_getname_spkt: make sure string is always 0-terminated

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Message-ID: <1371143387.2246.13.camel@bwh-desktop.uk.level5networks.com>
Date:	Thu, 13 Jun 2013 18:09:47 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	David Miller <davem@...emloft.net>
CC:	<dborkman@...hat.com>, <netdev@...r.kernel.org>
Subject: Re: [PATCH net] packet: packet_getname_spkt: make sure string is
 always 0-terminated

On Thu, 2013-06-13 at 18:05 +0100, Ben Hutchings wrote:
> On Thu, 2013-06-13 at 01:38 -0700, David Miller wrote:
> > From: Daniel Borkmann <dborkman@...hat.com>
> > Date: Wed, 12 Jun 2013 16:02:27 +0200
> > 
> > > uaddr->sa_data is exactly of size 14, which is hard-coded here and
> > > passed as a size argument to strncpy(). A device name can be of size
> > > IFNAMSIZ (== 16), meaning we might leave the destination string
> > > unterminated. Thus, use strlcpy() and also sizeof() while we're
> > > at it. We need to memset the data area beforehand, since strlcpy
> > > does not padd the remaining buffer with zeroes for user space, so
> > > that we do not possibly leak anything.
> > > 
> > > Signed-off-by: Daniel Borkmann <dborkman@...hat.com>
> > 
> > Applied, and queued up for -stable, thanks.
> 
> I don't think this should be applied anywhere.  Dropping support for
> 14-character device names is a regression.

...not that this actually prevents binding to 14-character device names;
it just means the name is then not reported back correctly.  Whatever,
it is a regression.  The fact that a 14-character name is not null-
terminated should be documented instead (I'm not sure where).

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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