fix math screwup that reintroduced a bias for upper_bounds in range

(2^30,2^31). Nothing in the tree yet requests random numbers bounded
by this range.

report jakob!deraadt; ok deraadt@

1 files changed, 2 insertions, 2 deletions

diff --git a/src/lib/libc/crypt/arc4random.c b/src/lib/libc/crypt/arc4random.c
index bbe42bd204..22b8d1f3c1 100644
--- a/src/lib/libc/crypt/arc4random.c
+++ b/src/lib/libc/crypt/arc4random.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: arc4random.c,v 1.18 2008/03/16 19:47:43 otto Exp $    */
+/*      $OpenBSD: arc4random.c,v 1.19 2008/06/04 00:50:23 djm Exp $     */
 
 /*
  * Copyright (c) 1996, David Mazieres <dm@uun.org>
@@ -231,7 +231,7 @@ arc4random_uniform(u_int32_t upper_bound)
                 min = 1 + ~upper_bound;         /* 2**32 - upper_bound */
         else {
                 /* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */
-                min = ((0xffffffff - (upper_bound << 2)) + 1) % upper_bound;
+                min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound;
         }
 #endif