Solved crash at GetExitCodeProcess in qprocess_win.cpp

[thamht4190]

Hi,
I see this crash from my customer's Windows. Can anyone tell what is reason for GetExitCodeProcess that leads Qt crash?
In my application, I create a process to run an .exe file. I use Qt 5.13.
Windows version: 10.0.17134.1, 64 bit.

STACK_TEXT:  
0000009a`e61fc4f0 00007ff8`1d9a7cce : 00007ff8`1d850000 00007ff8`1d850000 00000220`392f3a60 0000009a`e61fc710 : Qt5Core!QProcessPrivate::findExitCode+0x15
0000009a`e61fc520 00007ff8`1da3bc03 : 00000000`00000000 00007ff8`1ddede20 0000009a`e61fc699 00007ff8`1ddede20 : Qt5Core!QProcess::qt_static_metacall+0x1be
0000009a`e61fc5c0 00007ff8`1dad7389 : 00000220`397c3950 00000220`00000003 00000220`397c3950 00000000`00000000 : Qt5Core!QMetaObject::activate+0x5a3
0000009a`e61fc6e0 00007ff8`1da61080 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : Qt5Core!QWinEventNotifier::activated+0x49
0000009a`e61fc740 00007ff8`1da1b127 : 00000220`38db7010 00000000`00000001 00000220`38db7010 00000220`397c3950 : Qt5Core!QWinEventNotifier::event+0x180
0000009a`e61fc8a0 00007ff8`1da1b1e9 : 00000000`00000000 0000009a`e61fc998 ffffffff`ffffffff 00000220`397c3950 : Qt5Core!QCoreApplication::notify+0x67
0000009a`e61fc8f0 00007ff8`1da633f9 : 0000009a`e61fca00 00007ff8`7fe6031d 00000000`00000000 00000220`397c3d50 : Qt5Core!QCoreApplication::notifyInternal2+0xb9
0000009a`e61fc970 00007ff8`1da64d19 : 00000000`00000000 0000009a`e61fcac0 00000220`3937c601 00000000`00000024 : Qt5Core!QEventDispatcherWin32::activateEventNotifiers+0xa9
0000009a`e61fc9c0 00007ff8`1da1772b : 00000220`397c3d50 00000000`00000000 00000220`3944b700 00000000`00000000 : Qt5Core!QEventDispatcherWin32::processEvents+0x649
0000009a`e61ffb30 00007ff8`1d876742 : 00000220`395c49c0 00000220`395c49c0 00000220`397c3cf0 00000220`395c4950 : Qt5Core!QEventLoop::exec+0x1eb
0000009a`e61ffbb0 00007ff8`1d879009 : 00000220`395c49c0 00000220`395c49c0 00000220`395c4950 00000220`395c49c0 : Qt5Core!QThread::exec+0x92
0000009a`e61ffc00 00007ff8`80864034 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : Qt5Core!QThreadPrivate::start+0x189
0000009a`e61ffc40 00007ff8`82713691 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : kernel32!BaseThreadInitThunk+0x14
0000009a`e61ffc70 00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : ntdll!RtlUserThreadStart+0x21


FAULTING_SOURCE_LINE:  c:\users\qt\work\qt\qtbase\src\corelib\io\qprocess_win.cpp

FAULTING_SOURCE_FILE:  c:\users\qt\work\qt\qtbase\src\corelib\io\qprocess_win.cpp

FAULTING_SOURCE_LINE_NUMBER:  827

FAULTING_SOURCE_CODE:  
   823: void QProcessPrivate::findExitCode()
   824: {
   825:     DWORD theExitCode;
   826:     Q_ASSERT(pid);
>  827:     if (GetExitCodeProcess(pid->hProcess, &theExitCode)) {
   828:         exitCode = theExitCode;
   829:         crashed = (exitCode == 0xf291   // our magic number, see killProcess
   830:                    || (theExitCode >= 0x80000000 && theExitCode < 0xD0000000));
   831:     }
   832: }

Thanks!

[SGaist]

Hi,

Can you explain what your program is doing ?

[thamht4190]

Here is the code:
QtOSQuery.h

class QtOSQuery : public QObject
{
    Q_OBJECT
private:
    QProcess process;
public:
    explicit QtOSQuery(QObject *parent = nullptr);
    ~QtOSQuery();
    void callQuery(const QString& query,bool isAsync);
    void setProgram(const QString &programPath);
signals:
    void queryResult(const QJsonArray &value);
    void queryFinished();
    void queryError();
public slots:
    void onReadyReadStandardOutput();
};

QtOSQuery.cpp

QtOSQuery::QtOSQuery(QObject *parent) : QObject(parent)
{
    connect(&process,&QProcess::readyReadStandardOutput,this,&QtOSQuery::onReadyReadStandardOutput);
    connect(&process,QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished),this,[this](int exitCode, QProcess::ExitStatus exitStatus)
    {
        qDebug() << "os query finish with code " << exitCode << " status " << exitStatus;
        emit queryFinished();
    });
    connect(&process,&QProcess::errorOccurred,this,[this](QProcess::ProcessError error)
    {
        qDebug() << "os query error " << error;
        emit queryError();
    });
}

QtOSQuery::~QtOSQuery()
{
    qDebug() << "Call destructor QtOSQuery";
    if(process.isOpen())
        process.close();
}

void QtOSQuery::setProgram(const QString &programPath)
{
    process.setProgram(programPath);
}

void QtOSQuery::callQuery(const QString &query, bool isAsync)
{
    QStringList args;
    args << query;
    process.setArguments(args);
    process.open();
    if(!isAsync)
        process.waitForReadyRead();
}

void QtOSQuery::onReadyReadStandardOutput()
{
    QJsonDocument doc = QJsonDocument::fromJson(process.readAll());
    // output should always is json array
    Q_ASSERT(doc.isArray());
    emit(queryResult(doc.array()));
    process.terminate();
    QThread::msleep(100);
    process.close();
    if (process.state() != QProcess::NotRunning)
    {
        process.kill();
        QThread::msleep(100);
    }
}

Code where QtOSQuery is inited:

void CortexUtilGetOSInfo::getOSUserInfoFromConnectionPort(quint32 port)
{
    auto query = new QtOSQuery;
    query->setProgram(executableFilePath);

    connect(query,&QtOSQuery::queryResult,this,&CortexUtilGetOSInfo::getUserInfoSuccess);
    connect(query,&QtOSQuery::queryFinished,query,&QtOSQuery::deleteLater);

    // handle QProcess error
    connect(query,&QtOSQuery::queryError,query,&QtOSQuery::deleteLater);

    query->callQuery(QString(queryStr, true);

    // want to delete this query when this thread has 
    connect(QThread::currentThread(),&QThread::finished,query,&QObject::deleteLater);
}

Can you take a look @SGaist ?

[JonB]

@thamht4190
I would have thought the most likely reason for the "crash" is that pid->hProcess is "not valid" at the instant GetExitCodeProcess() is called.

Again, only a guess, but: in your onReadyReadStandardOutput() you terminate the process. Bearing in mind that is a slot called while the process is still very much active, I wonder what state things might be in internally when that returns. I would start by commenting out your "process termination" stuff and see where that gets you?

[thamht4190]

Thanks @JonB . The problem seems gone when I remove these "process terminate" code.