JNI crash outside JVM - EXCEPTION_ACCESS_VIOLATION - java-native-interface

Question

I needed a Java application to manipulate the Windows registry. To do this, I wrote some native C++ code and used JNI to call it.
For the most part it works. During testing I hadn't heard of a single problem. However, recently a user experienced a crash in the C++ code that brought down the JVM. The details are below. I have almost no C++ experience, so I think that is where I need the help. I think the issue is related to permissions, since when the Java app is run as an administrator, the problem goes away. The issue there is that not all our users will have admin privileges on their machines.
hs_err_pid log info:
#
# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x0000000076859083, pid=5316, tid=3116
#
# JRE version: 6.0_20-b02
# Java VM: Java HotSpot(TM) 64-Bit Server VM (16.3-b01 mixed mode windows-amd64 )
# Problematic frame:
# C [kernel32.dll+0x9083]
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#
Stack: [0x0000000013010000,0x0000000013110000], sp=0x000000001310f2d0, free space=3fc0000000000000000k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C [kernel32.dll+0x9083]
Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j my.package.WinRegUtils.SetKeyValue(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Z+0
j java.lang.Thread.run()V+11
v ~StubRoutines::call_stub
Here is the native code/method in question
JNIEXPORT jboolean JNICALL Java_my_package_WinRegUtils_SetKeyValue
(JNIEnv* env, jclass clazz, jstring jRootKey, jstring jKey, jstring jValueName, jstring jValueData, jstring jDataType)
{
bool success = false;
WCHAR* key_w;
WCHAR* valueName_w;
WCHAR* valueData_w;
WCHAR* dataType_w;
HKEY hKey;
const char* rootKey = env->GetStringUTFChars(jRootKey, false);
const char* key = env->GetStringUTFChars(jKey, false);
convertString(key, &key_w);
const char* valueName = env->GetStringUTFChars(jValueName, false);
convertString(valueName, &valueName_w);
const char* valueData = env->GetStringUTFChars(jValueData, false);
convertString(valueData, &valueData_w);
const char* dataType = env->GetStringUTFChars(jDataType, false);
convertString(dataType, &dataType_w);
HKEY root = GetRootHKEY(rootKey);
if (RegOpenKeyEx(root, key_w, 0, KEY_WRITE, &hKey) == ERROR_SUCCESS)
{
DWORD dwType;
BYTE* data;
DWORD length;
if (strcmp("REG_SZ", dataType) == 0)
{
dwType = REG_SZ;
data = (BYTE*)valueData_w;
length = wcslen(valueData_w) * sizeof(DWORD);
}
else if (strcmp("REG_DWORD", dataType) == 0)
{
dwType = REG_DWORD;
const DWORD intData = atoi(valueData);
data = (BYTE*)&intData;
length = sizeof(DWORD);
}
if (RegSetValueEx(hKey, valueName_w, 0, dwType, data, length) == ERROR_SUCCESS)
{
success = true;
RegCloseKey(hKey);
}
}
env->ReleaseStringUTFChars(jRootKey, rootKey);
env->ReleaseStringUTFChars(jKey, key);
env->ReleaseStringUTFChars(jValueName, valueName);
env->ReleaseStringUTFChars(jValueData, valueData);
env->ReleaseStringUTFChars(jDataType, dataType);
delete[] key_w, valueName_w, valueData_w, dataType_w;
return success;
}

Answer 1

To debug, add a few
printf("debug xxx");
fflush(stdout);
in
Java_my_package_WinRegUtils_SetKeyValue()
to isolate the failing line.