From 87b93c29be02f0a7ff9424b5e2b6431e20bd4c40 Mon Sep 17 00:00:00 2001
From: Tianlu Shao <shaotianlu@uniontech.com>
Date: Fri, 17 Dec 2021 10:27:55 +0800
Subject: [PATCH] QtConcurrent::run crashes on program exit

When an application is about to be closed and all the
destructors are called, if there isQtConcurrent::run on
the way, it crashes as the internal threadpool pointer
is nullptr.

Fixes: QTBUG-98901
Pick-to: 6.2 6.3
Change-Id: Idd84d1518fc6a225263e6666a0f1de2ccef79c82
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
---
 src/concurrent/qtconcurrentrunbase.h                 |  8 +++++++-
 .../qtconcurrentrun/tst_qtconcurrentrun.cpp          | 12 ++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/concurrent/qtconcurrentrunbase.h b/src/concurrent/qtconcurrentrunbase.h
index 6038d0e60cb..48703621469 100644
--- a/src/concurrent/qtconcurrentrunbase.h
+++ b/src/concurrent/qtconcurrentrunbase.h
@@ -93,7 +93,13 @@ public:
         promise.setRunnable(this);
         promise.reportStarted();
         QFuture<T> theFuture = promise.future();
-        parameters.threadPool->start(this, parameters.priority);
+
+        if (parameters.threadPool) {
+            parameters.threadPool->start(this, parameters.priority);
+        } else {
+            promise.reportCanceled();
+            promise.reportFinished();
+        }
         return theFuture;
     }
 
diff --git a/tests/auto/concurrent/qtconcurrentrun/tst_qtconcurrentrun.cpp b/tests/auto/concurrent/qtconcurrentrun/tst_qtconcurrentrun.cpp
index 235ffca0fcc..0ff98c42f5b 100644
--- a/tests/auto/concurrent/qtconcurrentrun/tst_qtconcurrentrun.cpp
+++ b/tests/auto/concurrent/qtconcurrentrun/tst_qtconcurrentrun.cpp
@@ -65,6 +65,7 @@ private slots:
     void crefFunction();
     void customPromise();
     void nonDefaultConstructibleValue();
+    void nullThreadPool();
 };
 
 void light()
@@ -1577,5 +1578,16 @@ void tst_QtConcurrentRun::nonDefaultConstructibleValue()
     QCOMPARE(future.result().value, 42);
 }
 
+// QTBUG-98901
+void tst_QtConcurrentRun::nullThreadPool()
+{
+    QThreadPool *pool = nullptr;
+    std::atomic<bool> isInvoked = false;
+    auto future = run(pool, [&] { isInvoked = true; });
+    future.waitForFinished();
+    QVERIFY(future.isCanceled());
+    QVERIFY(!isInvoked);
+}
+
 QTEST_MAIN(tst_QtConcurrentRun)
 #include "tst_qtconcurrentrun.moc"