[Xen-devel] [PATCH] x86/mm: fix checks against max_mapped_pfn

["Jan Beulich" <JBeulich@xxxxxxxx>]

This value is an inclusive one, i.e. this fixes an off-by-one in memory
sharing and an off-by-two in shadow code.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -1267,8 +1267,8 @@ int relinquish_shared_pages(struct domai
         return 0;
 
     p2m_lock(p2m);
-    for (gfn = p2m->next_shared_gfn_to_relinquish; 
-         gfn < p2m->max_mapped_pfn; gfn++ )
+    for ( gfn = p2m->next_shared_gfn_to_relinquish;
+          gfn <= p2m->max_mapped_pfn; gfn++ )
     {
         p2m_access_t a;
         p2m_type_t t;
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -3487,9 +3487,7 @@ int shadow_track_dirty_vram(struct domai
     struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
 
-    if (end_pfn < begin_pfn
-            || begin_pfn > p2m->max_mapped_pfn
-            || end_pfn >= p2m->max_mapped_pfn)
+    if ( end_pfn < begin_pfn || end_pfn > p2m->max_mapped_pfn + 1 )
         return -EINVAL;
 
     /* We perform p2m lookups, so lock the p2m upfront to avoid deadlock */

Attachment: x86-max-mapped-pfn-checks.patch
Description: Text document

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