linux-kernel - Re: [2.6.39-rc2, framebuffer] use after free oops

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Message-ID: <20110420105631.70695dfa@lxorguk.ukuu.org.uk>
Date:	Wed, 20 Apr 2011 10:56:31 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Bruno Prémont <bonbons@...ux-vserver.org>
Cc:	Daniel J Blueman <daniel.blueman@...il.com>,
	Paul Mundt <lethal@...ux-sh.org>, linux-fbdev@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [2.6.39-rc2, framebuffer] use after free oops

On Wed, 20 Apr 2011 08:05:35 +0200
Bruno Prémont <bonbons@...ux-vserver.org> wrote:

> On Wed, 20 Apr 2011 13:50:10 Daniel J Blueman <daniel.blueman@...il.com> wrote:
> > Any ideas on how best to address this issue [0], since it causes
> > silent corruption, or at best crashes?
> 
> There is probably no easy short-term fix to this... 

The short term fix would be to deliberately leak the buffer. That should
go into 2.6.39-rc right now with a comment explaining the situation.
Otherwise who knows what corruption may occur to user data if unlucky.

The other 'cheat' might be to tweak the API so the removal API isn't a
'destroy' interface but a 'shut down' and has a matching 'restart' one
for when the intelfb unloads at which point vga16fb can carry on with the
original fb_info 8)

Alan
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