[Xen-devel] [PATCH] x86/p2m: fixed p2m_change_type_range() start / end check

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

p2m_change_type_range() handles end > max_mapped_pfn, but not
start > max_mapped_pfn. Check the latter just after grabbing the
lock and bail if true.

Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
Suggested-by: George Dunlap <george.dunlap@xxxxxxxxxx>
---
 xen/arch/x86/mm/p2m.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index c53cab4..af46cd9 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -976,6 +976,13 @@ void p2m_change_type_range(struct domain *d,
     ASSERT(p2m_is_changeable(ot) && p2m_is_changeable(nt));
 
     p2m_lock(p2m);
+
+    if ( start > p2m->max_mapped_pfn )
+    {
+        p2m_unlock(p2m);
+        return;
+    }
+
     p2m->defer_nested_flush = 1;
 
     if ( unlikely(end > p2m->max_mapped_pfn) )
-- 
2.7.4


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