Date: Tue, 15 Jul 2014 17:49:27 -0700
From: Greg KH <greg@kroah.com>
To: Andrew Lutomirski <amluto@gmail.com>
Cc: Kamal Mostafa <kamal@canonical.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        stable <stable@vger.kernel.org>, kernel-team@lists.ubuntu.com,
        "H. Peter Anvin" <hpa@linux.intel.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Dirk Hohndel <dirk@hohndel.org>,
        Arjan van de Ven <arjan.van.de.ven@intel.com>,
        comex <comexk@gmail.com>,
        Alexander van Heukelum <heukelum@fastmail.fm>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: DO NOT APPLY: x86-64, espfix: Don't leak bits 31:16 of %esp
 returning to 16-bit stack
Message-ID: <20140716004927.GB7279@kroah.com>
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 <20140715235212.GC32651@kroah.com>
 <CAObL_7EzYQFWm0VsWbp6u67NWWTc=mN=4pQQOt7GYjwL0dzmrw@mail.gmail.com>
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On Tue, Jul 15, 2014 at 04:56:36PM -0700, Andrew Lutomirski wrote:
> On Tue, Jul 15, 2014 at 4:52 PM, Greg KH <greg@kroah.com> wrote:
> > On Tue, Jul 15, 2014 at 04:21:46PM -0700, Andrew Lutomirski wrote:
> >> On Tue, Jul 15, 2014 at 2:28 PM, Kamal Mostafa <kamal@canonical.com> wrote:
> >> > 3.13.11.5 -stable review patch.  If anyone has any objections, please let me know.
> >> >
> >> > ------------------
> >> >
> >> > From: "H. Peter Anvin" <hpa@linux.intel.com>
> >> >
> >> > commit 3891a04aafd668686239349ea58f3314ea2af86b upstream.
> >>
> >> Do not apply to any -stable release yet.  This causes nasty regressions on Xen.
> >
> > I thought you all found the Xen-regression-fix patch a few hours ago,
> > right?
> 
> That patch is insufficient: Xen guests still fail to initialize
> espfix64 correctly on SMP.  It's currently unclear that espfix64 can
> work at all on Xen -- it's may be rather fundamentally incompatible
> with the Xen hypercall IRET mechanism.  So it might need to be
> disabled entirely on Xen (and maybe Xen will fix the info leak in the
> hypervisor).

Ok, I'll pospone these all until the next round of stable releases next
week, Linus's tree should be fixed by then.

thanks,

greg k-h
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