linux-kernel - Re: [PATCH 4/7] hvc_console: Fix race between hvc_close and hvc

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Message-ID: <20100324150538.GA18581@amit-x200.redhat.com>
Date:	Wed, 24 Mar 2010 20:35:39 +0530
From:	Amit Shah <amit.shah@...hat.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [PATCH 4/7] hvc_console: Fix race between hvc_close and
	hvc_remove

On (Wed) Mar 24 2010 [11:37:21], Alan Cox wrote:
> On Sun, 21 Mar 2010 08:04:39 +1100
> Benjamin Herrenschmidt <benh@...nel.crashing.org> wrote:
> 
> > On Fri, 2010-03-19 at 08:18 -0700, Greg Kroah-Hartman wrote:
> > > From: Amit Shah <amit.shah@...hat.com>
> > > 
> > > Alan pointed out a race in the code where hvc_remove is invoked. The
> > > recent virtio_console work is the first user of hvc_remove().
> > 
> > This causes hangs during boot on pseries machines. Haven't had a chance
> > to track that down yet, but please revert
> > e74d098c66543d0731de62eb747ccd5b636a6f4c for now.
> 
> Its an exploitable hole so we should revert both the bug fix *and* the
> submission of the virtio console that makes the flaw triggerable, not jus
> tthe security fix.

If a fix isn't found in reasonable time, I will send a patch that
disables hot-unplug of virtio-console ports.

		Amit
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