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8218755: Refix Symbol leak in prepend_host_package_name

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Fix Symbol refcounting again, add comment and a test.

Reviewed-by: kbarrett, dholmes
This commit is contained in:
Coleen Phillimore 2019-02-13 07:22:09 -05:00
parent 2e4ac80e0c
commit 24b8feeb30
5 changed files with 172 additions and 35 deletions
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20
src/hotspot/share/classfile/classFileParser.cpp
View File

@ -5720,9 +5720,8 @@ void ClassFileParser::fill_instance_klass(InstanceKlass* ik, bool changed_by_loa
void ClassFileParser::update_class_name(Symbol* new_class_name) {
// Decrement the refcount in the old name, since we're clobbering it.
if (_class_name != NULL) {
_class_name->decrement_refcount();
}
_class_name->decrement_refcount();
_class_name = new_class_name;
// Increment the refcount of the new name.
// Now the ClassFileParser owns this name and will decrement in
@ -5753,11 +5752,16 @@ void ClassFileParser::prepend_host_package_name(const InstanceKlass* unsafe_anon
// characters. So, do a strncpy instead of using sprintf("%s...").
strncpy(new_anon_name + host_pkg_len + 1, (char *)_class_name->base(), class_name_len);
// Decrement old _class_name to avoid leaking.
_class_name->decrement_refcount();
// Create a symbol and update the anonymous class name.
Symbol* new_name = SymbolTable::new_symbol(new_anon_name,
// The new class name is created with a refcount of one. When installed into the InstanceKlass,
// it'll be two and when the ClassFileParser destructor runs, it'll go back to one and get deleted
// when the class is unloaded.
_class_name = SymbolTable::new_symbol(new_anon_name,
(int)host_pkg_len + 1 + class_name_len,
CHECK);
update_class_name(new_name);
}
}
@ -5861,7 +5865,8 @@ ClassFileParser::ClassFileParser(ClassFileStream* stream,
_has_vanilla_constructor(false),
_max_bootstrap_specifier_index(-1) {
update_class_name(name != NULL ? name : vmSymbols::unknown_class_name());
_class_name = name != NULL ? name : vmSymbols::unknown_class_name();
_class_name->increment_refcount();
assert(THREAD->is_Java_thread(), "invariant");
assert(_loader_data != NULL, "invariant");
@ -6086,8 +6091,7 @@ void ClassFileParser::parse_stream(const ClassFileStream* const stream,
Symbol* const class_name_in_cp = cp->klass_name_at(_this_class_index);
assert(class_name_in_cp != NULL, "class_name can't be null");
// Update _class_name which could be null previously
// to reflect the name in the constant pool
// Update _class_name to reflect the name in the constant pool
update_class_name(class_name_in_cp);
// Don't need to check whether this class name is legal or not.

75
test/hotspot/jtreg/runtime/defineAnonClass/AnonSymbolLeak.java Normal file
View File

@ -0,0 +1,75 @@
/*
* Copyright (c) 2019, 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.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
// This is copied from DefineAnon to test Symbol Refcounting for the package prepended name.
package p1;
import jdk.internal.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Opcodes;
import jdk.internal.misc.Unsafe;
class T {
static protected void test0() { System.out.println("test0 (public)"); }
static protected void test1() { System.out.println("test1 (protected)"); }
static /*package-private*/ void test2() { System.out.println("test2 (package)"); }
static private void test3() { System.out.println("test3 (private)"); }
}
public class AnonSymbolLeak {
private static final Unsafe UNSAFE = Unsafe.getUnsafe();
static Class<?> getAnonClass(Class<?> hostClass, final String className) {
final String superName = "java/lang/Object";
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);
cw.visit(Opcodes.V1_8, Opcodes.ACC_PUBLIC + Opcodes.ACC_FINAL + Opcodes.ACC_SUPER, className, null, superName, null);
MethodVisitor mv = cw.visitMethod(Opcodes.ACC_STATIC | Opcodes.ACC_PUBLIC, "test", "()V", null, null);
mv.visitMethodInsn(Opcodes.INVOKESTATIC, "p1/T", "test0", "()V", false);
mv.visitMethodInsn(Opcodes.INVOKESTATIC, "p1/T", "test1", "()V", false);
mv.visitMethodInsn(Opcodes.INVOKESTATIC, "p1/T", "test2", "()V", false);
mv.visitMethodInsn(Opcodes.INVOKESTATIC, "p1/T", "test3", "()V", false);
mv.visitInsn(Opcodes.RETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
final byte[] classBytes = cw.toByteArray();
Class<?> invokerClass = UNSAFE.defineAnonymousClass(hostClass, classBytes, new Object[0]);
UNSAFE.ensureClassInitialized(invokerClass);
return invokerClass;
}
public static void test() throws Throwable {
// AnonClass is injected into package p1.
System.out.println("Injecting from the same package (p1):");
Class<?> p1cls = getAnonClass(T.class, "AnonClass");
p1cls.getMethod("test").invoke(null);
}
public static void main(java.lang.String[] unused) throws Throwable {
test();
}
}

17
test/hotspot/jtreg/runtime/defineAnonClass/DefineAnon.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2016, 2019, 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
@ -27,6 +27,7 @@
* @library /testlibrary
* @modules java.base/jdk.internal.org.objectweb.asm
* java.management
* java.base/jdk.internal.misc
* @compile -XDignore.symbol.file=true DefineAnon.java
* @run main/othervm p1.DefineAnon
*/
@ -36,7 +37,7 @@ package p1;
import jdk.internal.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Opcodes;
import sun.misc.Unsafe;
import jdk.internal.misc.Unsafe;
class T {
@ -48,17 +49,7 @@ class T {
public class DefineAnon {
private static Unsafe getUnsafe() {
try {
java.lang.reflect.Field singleoneInstanceField = Unsafe.class.getDeclaredField("theUnsafe");
singleoneInstanceField.setAccessible(true);
return (Unsafe) singleoneInstanceField.get(null);
} catch (Throwable ex) {
throw new RuntimeException("Was unable to get Unsafe instance.");
}
}
static Unsafe UNSAFE = DefineAnon.getUnsafe();
private static final Unsafe UNSAFE = Unsafe.getUnsafe();
static Class<?> getAnonClass(Class<?> hostClass, final String className) {
final String superName = "java/lang/Object";

77
test/hotspot/jtreg/runtime/defineAnonClass/TestAnonSymbolLeak.java Normal file
View File

@ -0,0 +1,77 @@
/*
* Copyright (c) 2019, 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.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test TestAnonSymbolLeak
* @bug 8218755
* @requires vm.opt.final.ClassUnloading
* @modules java.base/jdk.internal.misc
* java.base/jdk.internal.org.objectweb.asm
* java.management
* @library /test/lib /runtime/testlibrary
* @build p1.AnonSymbolLeak
* @build sun.hotspot.WhiteBox
* @run main ClassFileInstaller sun.hotspot.WhiteBox
* sun.hotspot.WhiteBox$WhiteBoxPermission
* @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -Xlog:class+unload -XX:+WhiteBoxAPI TestAnonSymbolLeak
*/
import java.lang.reflect.Method;
import sun.hotspot.WhiteBox;
import jdk.test.lib.Asserts;
public class TestAnonSymbolLeak {
static String className = "p1.AnonSymbolLeak";
private static class ClassUnloadTestMain {
public static void test() throws Exception {
// Load the AnonSymbolLeak class in a new class loader, run it, which loads
// an unsafe anonymous class in the same package p1. Then unload it.
// Then test that the refcount of the symbol created for the prepended name doesn't leak.
ClassLoader cl = ClassUnloadCommon.newClassLoader();
Class<?> c = cl.loadClass(className);
c.getMethod("test").invoke(null);
cl = null; c = null;
ClassUnloadCommon.triggerUnloading();
}
}
public static WhiteBox wb = WhiteBox.getWhiteBox();
public static void main(String... args) throws Exception {
String oldName = "AnonClass";
String prependedName = "p1/AnonClass";
ClassUnloadCommon.failIf(wb.isClassAlive(className), "should not be loaded");
int countBeforeOld = wb.getSymbolRefcount(oldName);
int countBefore = wb.getSymbolRefcount(prependedName);
ClassUnloadTestMain.test();
ClassUnloadCommon.failIf(wb.isClassAlive(className), "should be unloaded");
int countAfterOld = wb.getSymbolRefcount(oldName);
int countAfter = wb.getSymbolRefcount(prependedName);
Asserts.assertEquals(countBeforeOld, countAfterOld); // no leaks to the old name
System.out.println("count before and after " + countBeforeOld + " " + countAfterOld);
Asserts.assertEquals(countBefore, countAfter); // no leaks to the prepended name
System.out.println("count before and after " + countBefore + " " + countAfter);
}
}

18
test/hotspot/jtreg/runtime/defineAnonClass/UnsafeDefMeths.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2018, 2019, 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
@ -28,6 +28,7 @@
* @library /testlibrary
* @modules java.base/jdk.internal.org.objectweb.asm
* java.management
* java.base/jdk.internal.misc
* @compile -XDignore.symbol.file=true UnsafeDefMeths.java
* @run main UnsafeDefMeths
*/
@ -35,7 +36,7 @@
import jdk.internal.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Type;
import sun.misc.Unsafe;
import jdk.internal.misc.Unsafe;
import java.lang.invoke.MethodType;
import java.lang.reflect.Field;
@ -57,18 +58,7 @@ import static jdk.internal.org.objectweb.asm.Opcodes.V1_8;
public class UnsafeDefMeths {
static final Unsafe UNSAFE;
static {
try {
Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
unsafeField.setAccessible(true);
UNSAFE = (Unsafe) unsafeField.get(null);
}
catch (Exception e) {
throw new InternalError(e);
}
}
private static final Unsafe UNSAFE = Unsafe.getUnsafe();
interface Resource {
Pointer ptr();