--- linux/mm/mremap.c.orig	2004-01-05 17:01:21.382104120 +0000
+++ linux/mm/mremap.c	2004-01-05 17:15:25.689749848 +0000
@@ -315,6 +315,10 @@
 	old_len = PAGE_ALIGN(old_len);
 	new_len = PAGE_ALIGN(new_len);
 
+	/* Don't allow the degenerate cases */
+	if (!old_len || !new_len)
+		goto out;
+
 	/* new_addr is only valid if MREMAP_FIXED is specified */
 	if (flags & MREMAP_FIXED) {
 		if (new_addr & ~PAGE_MASK)