1 /* 2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 /* 25 * @test 26 * @bug 8027445 27 * @summary String.equals() may be called with a length whose upper bits are not cleared 28 * @run main/othervm -XX:-UseOnStackReplacement -XX:-BackgroundCompilation TestStringEqualsBadLength 29 * 30 */ 31 32 import java.util.Arrays; 33 34 public class TestStringEqualsBadLength { 35 36 int v1; 37 int v2; 38 39 boolean m(String s1) { 40 int l = v2 - v1; // 0 - (-1) = 1. On 64 bit: 0xffffffff00000001 41 char[] arr = new char[l]; 42 arr[0] = 'a'; 43 String s2 = new String(arr); 44 // The string length is not reloaded but the value computed is 45 // reused so pointer computation must not use 46 // 0xffffffff00000001 47 return s2.equals(s1); 48 } 49 50 // Same thing with String.compareTo() 51 int m2(String s1) { 52 int l = v2 - v1; 53 char[] arr = new char[l+1]; 54 arr[0] = 'a'; 55 arr[1] = 'b'; 56 String s2 = new String(arr); 57 return s2.compareTo(s1); 58 } 59 60 // Same thing with equals() for arrays 61 boolean m3(char[] arr1) { 62 int l = v2 - v1; // 0 - (-1) = 1. On 64 bit: 0xffffffff00000001 63 char[] arr2 = new char[l]; 64 arr2[0] = 'a'; 65 return Arrays.equals(arr2, arr1); 66 } 67 68 static public void main(String[] args) { 69 TestStringEqualsBadLength tse = new TestStringEqualsBadLength(); 70 tse.v1 = -1; 71 tse.v2 = 0; 72 char[] arr = new char[1]; 73 arr[0] = 'a'; 74 for (int i = 0; i < 20000; i++) { 75 tse.m("a"); 76 tse.m2("ab"); 77 tse.m3(arr); 78 } 79 80 System.out.println("TEST PASSED"); 81 } 82 }