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[PATCH] Fix for a local frame leak in EnumMapper.cpp

From: Byeongcheol Lee <lineonking_at_gmail.com>
Date: Wed, 19 May 2010 18:26:40 -0500

Dear Subversion Developers:

I attach a patch for a local frame leak in EnumMapper.cpp, and the log
message follows here:

[[[
* subversion/bindings/javahl/native/CreateJ.cpp
 (getOrdinal): add a call to "PushLocalFrame" before the method
returns successfully without a Java exception.
]]]

To reproduce this bug, run your javaHL regression test under our
dynamic bug detector, JInn [http://userweb.cs.utexas.edu/~bclee/jinn]:

$env JAVA_TOOL_OPTIONS=-agentlib:jinn make check-javahl
...
Picked up JAVA_TOOL_OPTIONS: -agentlib:jinn
.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.E.
E.E.E.E.E.E.E.E.E.E.E
Time: 6.371
There were 51 errors:
1) testCreate(org.apache.subversion.javahl.SVNAdminTests)xtc.lang.blink.agent.JNIAssertionFailure:
Error: leak where local frame is not empty.
       at xtc.lang.blink.agent.JNIAssertionFailure.assertFail(JNIAssertionFailure.java:16)
       at org.apache.subversion.javahl.SVNClient.doImport(Native Method)
       at org.apache.subversion.javahl.SVNTests.setUp(SVNTests.java:239)
       at org.apache.subversion.javahl.RunTests.main(RunTests.java:116)
2) testSetRevProp(org.apache.subversion.javahl.SVNAdminTests)xtc.lang.blink.agent.JNIAssertionFailure:
Error: leak where local frame is not empty.
       at xtc.lang.blink.agent.JNIAssertionFailure.assertFail(JNIAssertionFailure.java:16)
       at org.apache.subversion.javahl.SVNClient.doImport(Native Method)
       at org.apache.subversion.javahl.SVNTests.setUp(SVNTests.java:239)
       at org.apache.subversion.javahl.RunTests.main(RunTests.java:116)
...

The local frame leak here happens when the number of calls to
"PushLocalFrame" is strictly more than "PopLocalFrame" when a native
method returns to JVM. This means that there was a call to
"PushLocalFrame" that does not have a corresponding call to
"PopLocalFrame" within the native method "SVNClicent.doImport" This
program run violates JNI programming rule:

 "Failing to place PopLocalFrame calls properly would lead to
undefined behavior, such as virtual machine crashes. "
 [http://java.sun.com/docs/books/jni/html/refs.html#27623]

I attached gdb the JVM and examined every call to "PushLocalFrame",
and I ended up with the source line 229 in EnumMapper.cpp:

In subversion/bindings/javahl/native/EnumMapper.cpp
  224 int EnumMapper::getOrdinal(const char *clazzName, jobject jenum)
  225 {
  226 JNIEnv *env = JNIUtil::getEnv();
  227
  228 // Create a local frame for our references
  229 env->PushLocalFrame(LOCAL_FRAME_SIZE);
  230 if (JNIUtil::isJavaExceptionThrown())
  231 return -1;
  232
  233 jclass clazz = env->FindClass(clazzName);
  234 if (JNIUtil::isJavaExceptionThrown())
  235 POP_AND_RETURN(-1);
  236
  237 jmethodID mid = env->GetMethodID(clazz, "ordinal", "()I");
  238 if (JNIUtil::isJavaExceptionThrown())
  239 POP_AND_RETURN(-1);
  240
  241 jint jorder = env->CallIntMethod(jenum, mid);
  242 if (JNIUtil::isJavaExceptionThrown())
  243 POP_AND_RETURN(-1);
  244
  245 return (int) jorder;
  246 }

When the C++ method "getOrdinal" does not receive any Java exception
from JNI calls at Line 233, 237, and 241, it does not
pop up the current local frame allocated at line 229.

Regards,
Byeong[PATCH] Fix for a local frame leak in EnumMapper.cpp

Received on 2010-05-20 01:27:09 CEST

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