--- linux-2.4.23/mm/mremap.c 2003-08-25 04:44:44.000000000 -0700
+++ linux-2.4.24/mm/mremap.c 2004-01-05 05:53:56.000000000 -0800
@@ -241,6 +241,13 @@

	if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
		goto out;
+	/*
+	* Allow new_len == 0 only if new_addr == addr
+	* to preserve truncation in place (that was working
+	* safe and some app may depend on it).
+	*/
+	if (unlikely(!new_len && new_addr != addr))
+		goto out;
	/* Check if the location we're moving into overlaps the
	* old location at all, and fail if it does.