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SubjectRe: [Stable-review] [22/45] KVM: Fix fs/gs reload oops with invalid ldt
On 11/26/2010 03:15 AM, Ben Hutchings wrote:
> Greg KH<gregkh@suse.de> wrote:
> > 2.6.32-stable review patch. If anyone has any objections, please let us know.
>
> Obviously it's a bit late now, but...
>
> > ------------------
> >
> > From: Avi Kivity<avi@redhat.com>
> >
> > commit 9581d442b9058d3699b4be568b6e5eae38a41493 upstream
> >
> > kvm reloads the host's fs and gs blindly, however the underlying segment
> > descriptors may be invalid due to the user modifying the ldt after loading
> > them.
> >
> > Fix by using the safe accessors (loadsegment() and load_gs_index()) instead
> > of home grown unsafe versions.
> >
> > This is CVE-2010-3698.
> >
> > Signed-off-by: Avi Kivity<avi@redhat.com>
> > Signed-off-by: Marcelo Tosatti<mtosatti@redhat.com>
> > Signed-off-by: Greg Kroah-Hartman<gregkh@suse.de>
> [...]
>
> Avi, you surely knew this commit was buggy (specifically for i386
> userland on an amd64 kernel) since you also committed:
>
> commit c8770e7ba63bb5dd8fe5f9d251275a8fa717fb78
> Author: Avi Kivity<avi@redhat.com>
> Date: Thu Nov 11 12:37:26 2010 +0200
>
> KVM: VMX: Fix host userspace gsbase corruption
>
> I realise it wasn't ready for stable as Linus only pulled it in
> 2.6.37-rc3, but surely that means this neither of the changes should
> have gone into 2.6.32.26. Why didn't you respond to the review??
>

I don't actually read those review emails, there are too many of them.

The fix will go into 2.6.32.stable in time. Fixing the vulnerability
was more important than i386-on-x86_64 anyway.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.



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