Fix a possible crash in process launcher

It may apparently happen that when calling QProcess::start()
we may receive a synchronous signal QProcess::errorOccurred()
from the process we are trying to start. In this case
the handler of the error signal might have removed the
process from m_processes hash, which invalidated the
"Process *& process" reference inside
LauncherSocketHandler::handleStartPacket(). So, using
process reference after calling start() may be dangerous.

Refactor ProcessStartHandler so that it stores the pointer
to the process it handles. The pointer to the handler
should still be valid after calling start(), since
the process itself is being deleted with a delay.

Make ProcessStartHandler a member of ProcessHelper. In this
way it's being reused in QProcessImpl and ProcessLauncher.

Fixes: QTCREATORBUG-26726
Change-Id: I8e3f39953035d76c83bbbb13bd78e3042ba2a14e
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

1 files changed, 11 insertions, 5 deletions

diff --git a/src/libs/utils/processutils.h b/src/libs/utils/processutils.h
index db3d18a7a37..74f3c1c8e20 100644
--- a/src/libs/utils/processutils.h
+++ b/src/libs/utils/processutils.h
@@ -38,23 +38,26 @@ enum class ProcessMode {
 
 class ProcessStartHandler {
 public:
+    ProcessStartHandler(QProcess *process) : m_process(process) {}
+
     void setProcessMode(ProcessMode mode) { m_processMode = mode; }
     void setWriteData(const QByteArray &writeData) { m_writeData = writeData; }
     QIODevice::OpenMode openMode() const;
-    void handleProcessStart(QProcess *process);
-    void handleProcessStarted(QProcess *process);
-    void setBelowNormalPriority(QProcess *process);
-    void setNativeArguments(QProcess *process, const QString &arguments);
+    void handleProcessStart();
+    void handleProcessStarted();
+    void setBelowNormalPriority();
+    void setNativeArguments(const QString &arguments);
 
 private:
     ProcessMode m_processMode = ProcessMode::Reader;
     QByteArray m_writeData;
+    QProcess *m_process;
 };
 
 class ProcessHelper : public QProcess
 {
 public:
-    ProcessHelper(QObject *parent) : QProcess(parent)
+    ProcessHelper(QObject *parent) : QProcess(parent), m_processStartHandler(this)
     {
 #if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0) && defined(Q_OS_UNIX)
         setChildProcessModifier([this] { setupChildProcess_impl(); });
@@ -65,6 +68,8 @@ public:
     void setupChildProcess() override { setupChildProcess_impl(); }
 #endif
 
+    ProcessStartHandler *processStartHandler() { return &m_processStartHandler; }
+
     using QProcess::setErrorString;
 
     void setLowPriority() { m_lowPriority = true; }
@@ -74,6 +79,7 @@ private:
     void setupChildProcess_impl();
     bool m_lowPriority = false;
     bool m_unixTerminalDisabled = false;
+    ProcessStartHandler m_processStartHandler;
 };
 
 } // namespace Utils