mm: Make copy_from_user() in migrate.c statically predictable

[net-next-2.6.git] / mm / migrate.c

diff --git a/mm/migrate.c b/mm/migrate.c
index 9a0db5bbabe4c93c0fce3ee7c24f13f2fbf84dc0..880bd592d38ea47af36f5f9b64323e8814d09f24 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1002,33 +1002,27 @@ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
 #define DO_PAGES_STAT_CHUNK_NR 16
        const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
        int chunk_status[DO_PAGES_STAT_CHUNK_NR];
-       unsigned long i, chunk_nr = DO_PAGES_STAT_CHUNK_NR;
-       int err;
 
-       for (i = 0; i < nr_pages; i += chunk_nr) {
-               if (chunk_nr > nr_pages - i)
-                       chunk_nr = nr_pages - i;
+       while (nr_pages) {
+               unsigned long chunk_nr;
 
-               err = copy_from_user(chunk_pages, &pages[i],
-                                    chunk_nr * sizeof(*chunk_pages));
-               if (err) {
-                       err = -EFAULT;
-                       goto out;
-               }
+               chunk_nr = nr_pages;
+               if (chunk_nr > DO_PAGES_STAT_CHUNK_NR)
+                       chunk_nr = DO_PAGES_STAT_CHUNK_NR;
+
+               if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages)))
+                       break;
 
                do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
 
-               err = copy_to_user(&status[i], chunk_status,
-                                  chunk_nr * sizeof(*chunk_status));
-               if (err) {
-                       err = -EFAULT;
-                       goto out;
-               }
-       }
-       err = 0;
+               if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
+                       break;
 
-out:
-       return err;
+               pages += chunk_nr;
+               status += chunk_nr;
+               nr_pages -= chunk_nr;
+       }
+       return nr_pages ? -EFAULT : 0;
 }
 
 /*