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8238676: jni crashes on accessing it from process exit hook
Reviewed-by: fparain, gziemski
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David Holmes committed Mar 3, 2020
1 parent 35ee1cb commit c42de93347d1647045f47dda7b50a1cd25db72b5
@@ -881,7 +881,7 @@ ifeq ($(call isTargetOs, windows), true)
BUILD_HOTSPOT_JTREG_EXECUTABLES_CFLAGS_exeFPRegs := -MT
BUILD_HOTSPOT_JTREG_EXCLUDE += exesigtest.c libterminatedThread.c
BUILD_HOTSPOT_JTREG_EXECUTABLES_LIBS_exejvm-test-launcher := jvm.lib

BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libatExit := jvm.lib
else
BUILD_HOTSPOT_JTREG_EXECUTABLES_LIBS_exejvm-test-launcher := -ljvm
BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libbootclssearch_agent += -lpthread
@@ -1517,6 +1517,7 @@ else
BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libgetphase001 += -lpthread
BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libgetphase002 += -lpthread
BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libterminatedThread += -lpthread
BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libatExit += -ljvm
endif

# This evaluation is expensive and should only be done if this target was
@@ -3681,7 +3681,8 @@ extern const struct JNIInvokeInterface_ jni_InvokeInterface;

// Global invocation API vars
volatile int vm_created = 0;
// Indicate whether it is safe to recreate VM
// Indicate whether it is safe to recreate VM. Recreation is only
// possible after a failed initial creation attempt in some cases.
volatile int safe_to_recreate_vm = 1;
struct JavaVM_ main_vm = {&jni_InvokeInterface};

@@ -3751,8 +3752,14 @@ static jint JNI_CreateJavaVM_inner(JavaVM **vm, void **penv, void *args) {
if (Atomic::xchg(&vm_created, 1) == 1) {
return JNI_EEXIST; // already created, or create attempt in progress
}

// If a previous creation attempt failed but can be retried safely,
// then safe_to_recreate_vm will have been reset to 1 after being
// cleared here. If a previous creation attempt succeeded and we then
// destroyed that VM, we will be prevented from trying to recreate
// the VM in the same process, as the value will still be 0.
if (Atomic::xchg(&safe_to_recreate_vm, 0) == 0) {
return JNI_ERR; // someone tried and failed and retry not allowed.
return JNI_ERR;
}

assert(vm_created == 1, "vm_created is true during the creation");
@@ -3945,9 +3952,14 @@ static jint attach_current_thread(JavaVM *vm, void **penv, void *_args, bool dae

Thread* t = Thread::current_or_null();
if (t != NULL) {
// If the thread has been attached this operation is a no-op
*(JNIEnv**)penv = ((JavaThread*) t)->jni_environment();
return JNI_OK;
// If executing from an atexit hook we may be in the VMThread.
if (t->is_Java_thread()) {
// If the thread has been attached this operation is a no-op
*(JNIEnv**)penv = ((JavaThread*) t)->jni_environment();
return JNI_OK;
} else {
return JNI_ERR;
}
}

// Create a thread and mark it as attaching so it will be skipped by the
@@ -4045,7 +4057,7 @@ static jint attach_current_thread(JavaVM *vm, void **penv, void *_args, bool dae
jint JNICALL jni_AttachCurrentThread(JavaVM *vm, void **penv, void *_args) {
HOTSPOT_JNI_ATTACHCURRENTTHREAD_ENTRY(vm, penv, _args);
if (vm_created == 0) {
HOTSPOT_JNI_ATTACHCURRENTTHREAD_RETURN((uint32_t) JNI_ERR);
HOTSPOT_JNI_ATTACHCURRENTTHREAD_RETURN((uint32_t) JNI_ERR);
return JNI_ERR;
}

@@ -4058,18 +4070,30 @@ jint JNICALL jni_AttachCurrentThread(JavaVM *vm, void **penv, void *_args) {

jint JNICALL jni_DetachCurrentThread(JavaVM *vm) {
HOTSPOT_JNI_DETACHCURRENTTHREAD_ENTRY(vm);
if (vm_created == 0) {
HOTSPOT_JNI_DETACHCURRENTTHREAD_RETURN(JNI_ERR);
return JNI_ERR;
}

JNIWrapper("DetachCurrentThread");

Thread* current = Thread::current_or_null();

// If the thread has already been detached the operation is a no-op
if (Thread::current_or_null() == NULL) {
if (current == NULL) {
HOTSPOT_JNI_DETACHCURRENTTHREAD_RETURN(JNI_OK);
return JNI_OK;
}

// If executing from an atexit hook we may be in the VMThread.
if (!current->is_Java_thread()) {
HOTSPOT_JNI_DETACHCURRENTTHREAD_RETURN((uint32_t) JNI_ERR);
return JNI_ERR;
}

VM_Exit::block_if_vm_exited();

JavaThread* thread = JavaThread::current();
JavaThread* thread = (JavaThread*) current;
if (thread->has_last_Java_frame()) {
HOTSPOT_JNI_DETACHCURRENTTHREAD_RETURN((uint32_t) JNI_ERR);
// Can't detach a thread that's running java, that can't work.
@@ -0,0 +1,73 @@
/*
* Copyright (c) 2020, 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.
*/
import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;

/*
* @test
* @bug 8238676
* @summary Check that attempting to use the JNI invocation API from an
* atexit handler fails as expected without crashing.
*
* @library /test/lib
* @run main/othervm/native TestAtExit
*/

public class TestAtExit {

// Using a nested class that invokes an enclosing method makes it
// easier to setup and use the native library.
static class Tester {
static {
System.loadLibrary("atExit");
}

// Record the fact we are using System.exit for termination
static native void setUsingSystemExit();

public static void main(String[] args) throws Exception {
if (args.length > 0) {
setUsingSystemExit();
System.exit(0);
}
}
}

public static void main(String[] args) throws Exception {
// We mustn't load Tester in this VM so we exec by name.
String main = "TestAtExit$Tester";

String jlp = "-Djava.library.path=" + System.getProperty("test.nativepath");
// First run will terminate via DestroyJavaVM
OutputAnalyzer output = ProcessTools.executeTestJvm(jlp, main);
output.shouldNotContain("Unexpected");
output.shouldHaveExitValue(0);
output.reportDiagnosticSummary();

// Second run will terminate via System.exit()
output = ProcessTools.executeTestJvm(jlp, main, "doExit");
output.shouldNotContain("Unexpected");
output.shouldHaveExitValue(0);
output.reportDiagnosticSummary();
}
}
@@ -0,0 +1,113 @@
/*
* Copyright (c) 2020, 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.
*/

#include <stdio.h>
#include <stdlib.h>

#include "jni.h"

static JavaVM *jvm;

static const char* jni_error_code(int ret) {
switch(ret) {
case JNI_OK: return "JNI_OK";
case JNI_ERR: return "JNI_ERR";
case JNI_EDETACHED: return "JNI_EDETACHED";
case JNI_EVERSION: return "JNI_EVERSION";
case JNI_ENOMEM: return "JNI_ENOMEM";
case JNI_EEXIST: return "JNI_EEXIST";
case JNI_EINVAL: return "JNI_EINVAL";
default: return "Invalid JNI error code";
}
}

static void report(const char* func, int ret_actual, int ret_expected) {
const char* ret = jni_error_code(ret_actual);
if (ret_actual == ret_expected) {
printf("%s returned %s as expected\n", func, ret);
} else {
printf("Unexpected JNI return code %s from %s\n", ret, func);
}
}

static int using_system_exit = 0; // Not System.exit by default

JNIEXPORT
void JNICALL Java_TestAtExit_00024Tester_setUsingSystemExit(JNIEnv* env, jclass c) {
using_system_exit = 1;
}

void at_exit_handler(void) {
printf("In at_exit_handler\n");

// We've saved the JavaVM from OnLoad time so we first try to
// get a JNIEnv for the current thread.
JNIEnv *env;
jint res = (*jvm)->GetEnv(jvm, (void **)&env, JNI_VERSION_1_2);
report("GetEnv", res, JNI_EDETACHED);
if (res == JNI_EDETACHED) {

// Test all of the Invocation API functions

res = (*jvm)->AttachCurrentThreadAsDaemon(jvm, (void **)&env, NULL);
report("AttachCurrentThreadAsDaemon", res, JNI_ERR);
res = (*jvm)->AttachCurrentThread(jvm, (void **)&env, NULL);
report("AttachCurrentThread", res, JNI_ERR);
res = (*jvm)->DetachCurrentThread(jvm);
report("DetachCurrentThread", res, JNI_ERR);

JavaVMInitArgs args;
args.version = JNI_VERSION_1_2;
res = JNI_GetDefaultJavaVMInitArgs(&args);
report("JNI_GetDefaultJavaVMInitArgs", res, JNI_OK);

JavaVM* jvm_p[1];
int nVMs;
res = JNI_GetCreatedJavaVMs(jvm_p, 1, &nVMs);
report("JNI_GetCreatedJavaVMs", res, JNI_OK);
// Whether nVMs is 0 or 1 depends on the termination path
if (nVMs == 0 && !using_system_exit) {
printf("Found 0 created VMs as expected\n");
} else if (nVMs == 1 && using_system_exit) {
printf("Found 1 created VM as expected\n");
} else {
printf("Unexpected number of created VMs: %d\n", nVMs);
}

res = (*jvm)->DestroyJavaVM(jvm);
report("DestroyJavaVM", res, JNI_ERR);

// Failure mode depends on the termination path
res = JNI_CreateJavaVM(jvm_p, (void**)&env, &args);
report("JNI_CreateJavaVM", res, using_system_exit ? JNI_EEXIST : JNI_ERR);
}
// else test has already failed
}

jint JNI_OnLoad(JavaVM *vm, void *reserved) {
printf("JNI_OnLoad: registering atexit handler\n");
jvm = vm;
atexit(at_exit_handler);

return JNI_VERSION_1_1;
}

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