Index: grub2-1.99/grub-core/disk/lvm.c
===================================================================
--- grub2-1.99.orig/grub-core/disk/lvm.c	2011-04-18 21:16:16.000000000 +0000
+++ grub2-1.99/grub-core/disk/lvm.c	2015-07-16 03:05:41.624035502 +0000
@@ -629,7 +629,8 @@
 		    goto lvs_segment_fail;
 		  p += sizeof("type = \"") - 1;
 
-		  lv->size += seg->extent_count * vg->extent_size;
+		  lv->size += ((grub_uint64_t) seg->extent_count
+				* (grub_uint64_t) vg->extent_size);
 
 		  if (grub_memcmp (p, "striped\"",
 				   sizeof ("striped\"") - 1) == 0)