[Xen-devel] [PATCH] do_memory_op: cleanup if copy_to_guest fails

[Olaf Hering <olaf@xxxxxxxxx>]

Undo the page allocation in the ulikely event the copy_to_guest fails.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

---

I have not exercised this code path, it was found during code inspection in 4.0

 xen/common/memory.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- xen-unstable.hg-4.1.22548.orig/xen/common/memory.c
+++ xen-unstable.hg-4.1.22548/xen/common/memory.c
@@ -82,7 +82,10 @@ static void increase_reservation(struct
         {
             mfn = page_to_mfn(page);
             if ( unlikely(__copy_to_guest_offset(a->extent_list, i, &mfn, 1)) )
+            {
+                free_domheap_pages(page, a->extent_order);
                 goto out;
+            }
         }
     }
 
@@ -144,7 +147,13 @@ static void populate_physmap(struct memo
 
                 /* Inform the domain of the new page's machine address. */ 
                 if ( unlikely(__copy_to_guest_offset(a->extent_list, i, &mfn, 
1)) )
+                {
+                    for ( j = 0; j < (1 << a->extent_order); j++ )
+                        set_gpfn_from_mfn(mfn + j, INVALID_M2P_ENTRY);
+                    guest_physmap_remove_page(d, gpfn, mfn, a->extent_order);
+                    free_domheap_pages(page, a->extent_order);
                     goto out;
+                }
             }
         }
     }

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