netdev - Re: [PATCH] wireless: wext: allocate space for NULL-termination for 32byte SSIDs

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Date:	Wed, 16 Dec 2009 09:20:33 +0100
From:	Johannes Berg <johannes@...solutions.net>
To:	Daniel Mack <daniel@...aq.de>
Cc:	David Miller <davem@...emloft.net>, linux-kernel@...r.kernel.org,
	dcbw@...hat.com, m.hirsch@...mfeld.com, netdev@...r.kernel.org,
	libertas-dev@...ts.infradead.org, stable@...nel.org,
	linux-wireless@...r.kernel.org
Subject: Re: [PATCH] wireless: wext: allocate space for NULL-termination
 for 32byte SSIDs

On Wed, 2009-12-16 at 11:58 +0800, Daniel Mack wrote:

> > If this is used in a GET, then it will be filled up to 32 bytes by the
> > get handler, and the trailing \0 your patch reserves will never be
> > copied into userspace.
> 
> The problem is the GET case. The libertas driver copies ssid_len
> characters here and appends a trailing \0, which my patch caught now and
> which caused memory corruption in before.
> 
> From what I've seen, libertas _does_ treat the extra data correctly
> at all places, I checked it several times now. (Btw, the %s format
> string you pointed out all use print_ssid() to properly escape all
> non-printable characters, so they're rules out, too).

Oh, ok, print_ssid() is correct of course, it gets the length.

> I'll send a patch to fix the flaw in libertas.

Thanks.

johannes

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