Re: [Xen-devel] [PATCH] Unified shutdown code

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 10/9/07 22:22, "Cihula, Joseph" <joseph.cihula@xxxxxxxxx> wrote:

> But the purpose of centralizing it was so that the hook into sboot's
> shutdown wouldn't need to be in multiple place.  And the reason to hook
> into sboot's shutdown (which also supports the halt action) even though
> the system is being halt'ed is so that we don't leave some path that
> allows the system to be subverted or misused while still having
> privileged access to the TPM, etc.

Why is Xen running a halt loop on every CPU any more exploitable than Xen
running normal Xen code on every CPU? If every CPU is spinning on HLT with
interrupts disabled then the only signals that will change state are things
like NMI, INIT, reset?

 -- Keir

> That said, I'm not aware of any exploitable conditions/paths/environment
> when Xen is placed in a halt loop (at least none that JTAG users
> wouldn't already have without waiting for the system to halt), so I
> suppose that this extra bit of caution is not really necessary.  But if
> the EARLY_FAIL behavior gets changed back to halt, is there any harm?



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel