[education/kstars] kstars/auxiliary: Fix crash when a stale EkosLive dialog response arrives after the dialog was dismissed

Git commit 2fb72b3135d957dd0b743b26dbb573b29dbc46d4 by Jasem Mutlaq, on behalf of Ilia Belov.
Committed on 28/07/2026 at 07:03.
Pushed by mutlaqja into branch 'master'.

Fix crash when a stale EkosLive dialog response arrives after the dialog was dismissed

`KSMessageBox` is a reused singleton; buttons of a dismissed dialog stay as its children until the next dialog calls `reset()`. `selectResponse()` matches a button by text and clicks it unconditionally, and `Message::processDialogResponse()` forwards remote `dialog_get_response` frames without validation. So a response sent after the dialog was already dismissed (closed on the desktop, timed out, or a duplicate tap) clicks a stale button, re-fires `accepted()`/`rejected()` and crashes KStars with SIGSEGV during widget teardown.

Reproduce:

1. Open the StellarMate app.
2. Trigger any Ekos dialog ("Cover the telescope…").
3. Dismiss it on the KStars desktop.
4. Tap a button for that dialog in the app → crash.

Fix: in `selectResponse()`, ignore responses when the dialog is not visible, and ignore duplicates while a response is in flight (`m_ResponseInProgress`, cleared on accepted/rejected/reset). Normal single-response behavior unchanged.

M  +17   -0    kstars/auxiliary/ksmessagebox.cpp
M  +5    -0    kstars/auxiliary/ksmessagebox.h

https://invent.kde.org/education/kstars/-/commit/2fb72b3135d957dd0b743b26dbb573b29dbc46d4

diff --git a/kstars/auxiliary/ksmessagebox.cpp b/kstars/auxiliary/ksmessagebox.cpp
index 65ba058bbe..cb4f0c51a4 100644
--- a/kstars/auxiliary/ksmessagebox.cpp
+++ b/kstars/auxiliary/ksmessagebox.cpp
@@ -46,12 +46,14 @@ KSMessageBox::KSMessageBox() : QMessageBox()
 
     connect(this, &KSMessageBox::rejected, [this]()
     {
+        m_ResponseInProgress = false;
         m_ProgressTimer.stop();
         Q_EMIT newMessage(QJsonObject());
     });
 
     connect(this, &KSMessageBox::accepted, [this]()
     {
+        m_ResponseInProgress = false;
         m_ProgressTimer.stop();
         Q_EMIT newMessage(QJsonObject());
     });
@@ -157,6 +159,7 @@ void KSMessageBox::setupTimeout(quint32 timeout)
 
 void KSMessageBox::reset()
 {
+    m_ResponseInProgress = false;
     m_ProgressTimer.stop();
     resetTimeout();
 
@@ -296,12 +299,26 @@ QJsonObject KSMessageBox::createMessageObject()
 
 bool KSMessageBox::selectResponse(const QString &button)
 {
+    // Ignore responses when no dialog is currently shown. The message box is a
+    // reused singleton, so the buttons of a previously dismissed dialog linger as
+    // children; clicking one of those would re-emit accepted()/rejected() and could
+    // tear down widgets while their signals are still being processed.
+    if (!isVisible())
+        return false;
+
+    // Ignore duplicate or re-entrant responses. animateClick() dismisses the dialog
+    // asynchronously, so a second response (e.g. a remote EkosLive client sending
+    // dialog_get_response repeatedly) could arrive before the dialog hides.
+    if (m_ResponseInProgress)
+        return false;
+
     for (const auto oneButton : findChildren<QPushButton * >())
     {
         const QString buttonText = oneButton->text().remove("&");
 
         if (button == buttonText)
         {
+            m_ResponseInProgress = true;
             oneButton->animateClick();
             return true;
         }
diff --git a/kstars/auxiliary/ksmessagebox.h b/kstars/auxiliary/ksmessagebox.h
index 0b8f8a71b9..079f90c242 100644
--- a/kstars/auxiliary/ksmessagebox.h
+++ b/kstars/auxiliary/ksmessagebox.h
@@ -63,6 +63,11 @@ class KSMessageBox: public QMessageBox
         // Dialog timeout in seconds
         quint32 m_Timeout {60};
 
+        // True while a button response is being processed. Guards against duplicate
+        // or stale programmatic responses (e.g. from a remote EkosLive client) that
+        // would otherwise click a button on an already-dismissed dialog.
+        bool m_ResponseInProgress {false};
+
         static KSMessageBox *m_Instance;
 
         void reset();