src/share/classes/com/sun/crypto/provider/ISO10126Padding.java

rev 12526 : 8171252: Improve exception checking
8158517: Minor optimizations to ISO10126PADDING
Reviewed-by: ascarpino, mschoene

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this

@@ -61,19 +61,20 @@
         throws ShortBufferException
     {
         if (in == null)
             return;
 
-        if ((off + len) > in.length) {
+        int idx = Math.addExact(off, len);
+        if (idx > in.length) {
             throw new ShortBufferException("Buffer too small to hold padding");
         }
 
         byte paddingOctet = (byte) (len & 0xff);
-        byte[] padding = new byte[len];
+        byte[] padding = new byte[len - 1];
         SunJCE.getRandom().nextBytes(padding);
-        padding[len-1] = paddingOctet;
-        System.arraycopy(padding, 0, in, off, len);
+        System.arraycopy(padding, 0, in, off, len - 1);
+        in[idx - 1] = paddingOctet;
         return;
     }
 
     /**
      * Returns the index where the padding starts.

@@ -92,18 +93,19 @@
         if ((in == null) ||
             (len == 0)) { // this can happen if input is really a padded buffer
             return 0;
         }
 
-        byte lastByte = in[off + len - 1];
+        int idx = Math.addExact(off, len);
+        byte lastByte = in[idx - 1];
         int padValue = (int)lastByte & 0x0ff;
         if ((padValue < 0x01)
             || (padValue > blockSize)) {
             return -1;
         }
 
-        int start = off + len - ((int)lastByte & 0x0ff);
+        int start = idx - padValue;
         if (start < off) {
             return -1;
         }
 
         return start;