[jdk11u-dev] RFR: 8315135: Memory leak in the native implementation of Pack200.Unpacker.unpack()

[Volker Simonis]

This issue was found by Yakov Shafranovich (yakovsh at amazon.com) who also provided the reproducer and proposed a fix.

The native implementation of the `Pack200.Unpacker` class included in OpenJDK 8 and 11 has a native and heap memory leak that gets triggered when corrupted files are processed. If the native `NativeUnpack::start()` method throws an exception (because of a corrupted input file) its caller `NativeUnpack::run()` fails to call the native `NativeUnpack::finish()` method which is responsible for freeing the allocated native memory and releasing the created global JNI handles. A Java application processing large number of malformed Pack200 files will eventually run either out of native memory or out of heap space and exit with an `OutOfMemoryError`.

The problem can be demonstrated with the following short test program which will exit with an `OutOfMemoryError` quite quickly if run with `java -Xmx32m NativePack200POC`:


import java.io.*;
import java.util.jar.*;

@SuppressWarnings("removal")
public class NativePack200POC {
  public static void main(String[] args) {
    try {
      ByteArrayInputStream in = new ByteArrayInputStream("foobar".getBytes());
      for(int i=0; i < 1_000_000; i++) {
        try {
          JarOutputStream out = new JarOutputStream(new ByteArrayOutputStream());
          Pack200.Unpacker unpacker = Pack200.newUnpacker();
          unpacker.unpack(in, out);
        } catch (IOException e) {
        }
      }
    } catch (OutOfMemoryError e) {
      System.out.println(e);
      throw e;
    }
  }
}


The problem can be worked around by disabling the native Pack200 implementation with `-Dcom.sun.java.util.jar.pack.disable.native=true` but the default setting is `-Dcom.sun.java.util.jar.pack.disable.native=false`.

Notice that this bug can not be fixed in HEAD because the Pack200 functionality has been removed in JDK 14 (https://openjdk.org/jeps/367). I therefore propose to fix this in jdk11u-dev first and then downport the fix to jdk8u-dev as well.


-------------

Commit messages:
 - 8315135: Memory leak in the native implementation of Pack200O.Unpacker.unpack()

Changes: https://git.openjdk.org/jdk11u-dev/pull/2100/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2100&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315135
  Stats: 61 lines in 3 files changed: 60 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2100.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2100/head:pull/2100

PR: https://git.openjdk.org/jdk11u-dev/pull/2100