From dc4972a4e2f3fee1663bd0670dfc4cd798d5f9b2 Mon Sep 17 00:00:00 2001
From: Ian Campbell <ian.campbell@citrix.com>
Date: Fri, 4 Mar 2011 17:38:21 +0000
Subject: [PATCH] xen/p2m/m2p/gnttab: do not add failed grant maps to m2p
 override

The caller will not undo a mapping which failed and therefore the
override will not be removed.

This is especially bad in the case of GNTMAP_contains_pte mapping type
mappings where m2p_add_override will destroy the kernel mapping of the
page.

This was observed via a failure of map_grant_pages in gntdev_mmap (due
to userspace using a bad grant reference), which left the page in
question unmapped (because it was a GNTMAP_contains_pte mapping) which
led to a crash later on.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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