diff -r 4142bfd01e02 tools/libxc/xc_linux_build.c
--- a/tools/libxc/xc_linux_build.c	Thu Jun  1 11:25:02 2006 +0100
+++ b/tools/libxc/xc_linux_build.c	Thu Jun  1 14:28:41 2006 -0400
@@ -714,7 +714,16 @@ static int setup_guest(int xc_handle,
         vstack_end       = vstack_start + PAGE_SIZE;
         v_end            = (vstack_end + (1UL<<22)-1) & ~((1UL<<22)-1);
         if ( (v_end - vstack_end) < (512UL << 10) )
-            v_end += 1UL << 22; /* Add extra 4MB to get >= 512kB padding. */
+        {
+            /* Check if v_end is wrapping around to 0 */
+            if ( (1UL << 22) < -(v_end) )
+                v_end += 1UL << 22; /* Add extra 4MB to get >= 512kB padding. */
+            else
+            {
+                ERROR("v_end wrapped around to 0");
+                goto error_out;
+            }
+        }
 #define NR(_l,_h,_s) \
     (((((_h) + ((1UL<<(_s))-1)) & ~((1UL<<(_s))-1)) - \
     ((_l) & ~((1UL<<(_s))-1))) >> (_s))