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// Copyright 2021 Code Intelligence GmbH
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* A native wrapper around the FuzzTargetRunner Java class that executes it as a
* libFuzzer fuzz target.
*/
#include "fuzz_target_runner.h"
#ifndef _WIN32
#include <dlfcn.h>
#endif
#include <jni.h>
#include <iostream>
#include <limits>
#include <string>
#include <vector>
#include "com_code_intelligence_jazzer_driver_FuzzTargetRunner.h"
extern "C" int LLVMFuzzerRunDriver(int *argc, char ***argv,
int (*UserCb)(const uint8_t *Data,
size_t Size));
namespace {
jclass gRunner;
jmethodID gRunOneId;
JavaVM *gJavaVm;
JNIEnv *gEnv;
// A libFuzzer-registered callback that outputs the crashing input, but does
// not include a stack trace.
void (*gLibfuzzerPrintCrashingInput)() = nullptr;
int testOneInput(const uint8_t *data, const std::size_t size) {
JNIEnv &env = *gEnv;
jint jsize =
std::min(size, static_cast<size_t>(std::numeric_limits<jint>::max()));
int res = env.CallStaticIntMethod(gRunner, gRunOneId, data, jsize);
if (env.ExceptionCheck()) {
env.ExceptionDescribe();
_Exit(1);
}
return res;
}
} // namespace
namespace jazzer {
void DumpJvmStackTraces() {
JNIEnv *env = nullptr;
if (gJavaVm->AttachCurrentThread(reinterpret_cast<void **>(&env), nullptr) !=
JNI_OK) {
std::cerr << "WARN: AttachCurrentThread failed in DumpJvmStackTraces"
<< std::endl;
return;
}
jmethodID dumpStack =
env->GetStaticMethodID(gRunner, "dumpAllStackTraces", "()V");
if (env->ExceptionCheck()) {
env->ExceptionDescribe();
return;
}
env->CallStaticVoidMethod(gRunner, dumpStack);
if (env->ExceptionCheck()) {
env->ExceptionDescribe();
return;
}
// Do not detach as we may be the main thread (but the JVM exits anyway).
}
} // namespace jazzer
[[maybe_unused]] jint
Java_com_code_1intelligence_jazzer_driver_FuzzTargetRunner_startLibFuzzer(
JNIEnv *env, jclass runner, jobjectArray args) {
gEnv = env;
env->GetJavaVM(&gJavaVm);
gRunner = reinterpret_cast<jclass>(env->NewGlobalRef(runner));
gRunOneId = env->GetStaticMethodID(runner, "runOne", "(JI)I");
if (gRunOneId == nullptr) {
env->ExceptionDescribe();
_Exit(1);
}
int argc = env->GetArrayLength(args);
if (env->ExceptionCheck()) {
env->ExceptionDescribe();
_Exit(1);
}
std::vector<std::string> argv_strings;
std::vector<const char *> argv_c;
for (jsize i = 0; i < argc; i++) {
auto arg_jni =
reinterpret_cast<jbyteArray>(env->GetObjectArrayElement(args, i));
if (arg_jni == nullptr) {
env->ExceptionDescribe();
_Exit(1);
}
jbyte *arg_c = env->GetByteArrayElements(arg_jni, nullptr);
if (arg_c == nullptr) {
env->ExceptionDescribe();
_Exit(1);
}
std::size_t arg_size = env->GetArrayLength(arg_jni);
if (env->ExceptionCheck()) {
env->ExceptionDescribe();
_Exit(1);
}
argv_strings.emplace_back(reinterpret_cast<const char *>(arg_c), arg_size);
env->ReleaseByteArrayElements(arg_jni, arg_c, JNI_ABORT);
if (env->ExceptionCheck()) {
env->ExceptionDescribe();
_Exit(1);
}
}
for (jsize i = 0; i < argc; i++) {
argv_c.emplace_back(argv_strings[i].c_str());
}
// Null-terminate argv.
argv_c.emplace_back(nullptr);
const char **argv = argv_c.data();
return LLVMFuzzerRunDriver(&argc, const_cast<char ***>(&argv), testOneInput);
}
[[maybe_unused]] void
Java_com_code_1intelligence_jazzer_driver_FuzzTargetRunner_printCrashingInput(
JNIEnv *, jclass) {
if (gLibfuzzerPrintCrashingInput == nullptr) {
std::cerr << "<not available>" << std::endl;
} else {
gLibfuzzerPrintCrashingInput();
}
}
[[maybe_unused]] void
Java_com_code_1intelligence_jazzer_driver_FuzzTargetRunner__1Exit(
JNIEnv *, jclass, jint exit_code) {
_Exit(exit_code);
}
// We apply a patch to libFuzzer to make it call this function instead of
// __sanitizer_set_death_callback to pass us the death callback.
extern "C" [[maybe_unused]] void __jazzer_set_death_callback(
void (*callback)()) {
gLibfuzzerPrintCrashingInput = callback;
#ifndef _WIN32
void *sanitizer_set_death_callback =
dlsym(RTLD_DEFAULT, "__sanitizer_set_death_callback");
if (sanitizer_set_death_callback != nullptr) {
(reinterpret_cast<void (*)(void (*)())>(sanitizer_set_death_callback))(
[]() {
::jazzer::DumpJvmStackTraces();
gLibfuzzerPrintCrashingInput();
// Ideally, we would be able to perform a graceful shutdown of the
// JVM. However, doing this directly results in a nested bug report by
// ASan or UBSan, likely because something about the stack/thread
// context in which they generate reports is incompatible with the JVM
// shutdown process. use_sigaltstack=0 does not help though, so this
// might be on us.
});
}
#endif
}
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