[PATCH 4/7] hvc_console: Fix race between hvc_close and hvc_remove

[Amit Shah]

On (Wed) Mar 24 2010 [11:37:21], Alan Cox wrote:
> On Sun, 21 Mar 2010 08:04:39 +1100
> Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:
> 
> > On Fri, 2010-03-19 at 08:18 -0700, Greg Kroah-Hartman wrote:
> > > From: Amit Shah <amit.shah at redhat.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