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RE: [Xen-devel] Xen 4.0.0x allows for data corruption in Dom0

To: "Joanna Rutkowska" <joanna@xxxxxxxxxxxxxxxxxxxxxx>, "Jeremy Fitzhardinge" <jeremy@xxxxxxxx>
Subject: RE: [Xen-devel] Xen 4.0.0x allows for data corruption in Dom0
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Tue, 9 Mar 2010 11:18:28 +1100
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Thread-topic: [Xen-devel] Xen 4.0.0x allows for data corruption in Dom0
> > I can't think of a Xen failure-mode which would cause these symptoms
> > without also being massively obvious in other cases.  (But "I can't
> > think of..." is where all the best bugs hide.)
> >
> But the corruptions always happen in 32-bytes chunks, which might
> suggest it's not a page-related problem (e.g. wrongly re-used page),
> in that case we would be observing (at least sometimes) much bigger
> chunks of corrupted data, I think.

Based on your hex dump output, it appears to be the first 32 bytes of a
page, which does lend itself to the idea that it's a page allocated for
something with only the first 32 bytes used.

You've stated that you are no longer set up to reproduce it, which is
unfortunate. If you find yourself in a position to try it again there
are bunch of things you could try to figure out on which end of the copy
the problem lies.


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