QWidget/QDialog set Qt::WA_DeleteOnClose will crash the application when close the main window

ThreeStones

The code is very simple, just create a QPushButton and a QDialog.
mymac:> qmake -v
QMake version 3.1
Using Qt version 5.11.2 in /usr/local/Cellar/qt/5.11.2_1/lib

mainwindow.cpp

MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
}

MainWindow::~MainWindow()
{
delete ui;
}

void
MainWindow::on_pushButton_clicked()
{
MyDialog* dialog = new MyDialog(this);
dialog->setAttribute(Qt::WA_DeleteOnClose,true);
dialog->show();
}

mydialog.cpp:

MyDialog::MyDialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::MyDialog)
{
ui->setupUi(this);
}

MyDialog::~MyDialog()
{
delete ui;
}

when running on Mac,
mymac:> ./dialogtest.app/Contents/MacOS/dialogtest
dialogtest(72739,0x7fffb02bf380) malloc: *** error for object 0x7ffee71ce978: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6 (core dumped)

crash report generated by MacOs:

Process: dialogtest [72739]
Path: /Users/USER/*/dialogtest.app/Contents/MacOS/dialogtest
Identifier: com.yourcompany.dialogtest
Version: 0
Code Type: X86-64 (Native)
Parent Process: bash [86735]
Responsible: dialogtest [72739]
User ID: 501

Date/Time: 2019-01-25 23:19:02.812 -0800
OS Version: Mac OS X 10.13.6 (17G3025)
Report Version: 12
Anonymous UUID: 96A1AF96-6E32-4D77-67FA-CA4895814B40

Sleep/Wake UUID: 77FB1050-2557-4CAB-BFD8-29E3D5CDC929

Time Awake Since Boot: 420000 seconds
Time Since Wake: 5100 seconds

System Integrity Protection: disabled

Crashed Thread: 0 Dispatch queue: com.apple.main-thread

Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY

Application Specific Information:
abort() called
*** error for object 0x7ffee71ce978: pointer being freed was not allocated

Thread 0 Crashed:: 0 libsystem_kernel.dylib 1 libsystem_pthread.dylib 2 libsystem_c.dylib 3 libsystem_malloc.dylib 4 org.qt-project.QtCore 5 org.qt-project.QtWidgets 6 org.qt-project.QtWidgets 7 org.qt-project.QtWidgets 8 org.qt-project.QtWidgets 9 org.qt-project.QtCore 10 org.qt-project.QtCore 11 libqcocoa.dylib 12 libqcocoa.dylib 13 com.apple.CoreFoundation 14 com.apple.CoreFoundation 15 com.apple.CoreFoundation 16 com.apple.CoreFoundation 17 com.apple.CoreFoundation 18 com.apple.HIToolbox 19 com.apple.HIToolbox 20 com.apple.HIToolbox 21 com.apple.AppKit 22 com.apple.AppKit 23 com.apple.AppKit 24 libqcocoa.dylib 25 org.qt-project.QtCore 26 org.qt-project.QtCore 27 com.yourcompany.dialogtest 28 libdyld.dylib Dispatch queue: com.apple.main-thread
0x00007fff779c9b66 __pthread_kill + 10
0x00007fff77b94080 pthread_kill + 333
0x00007fff779251ae abort + 127
0x00007fff77a23822 free + 521
0x00000001097172c2 QObject::event(QEvent*) + 146
0x0000000108a8c798 QWidget::event(QEvent*) + 4776
0x0000000108b9cfa5 QMainWindow::event(QEvent*) + 277
0x0000000108a51a7d QApplicationPrivate::notify_helper(QObject*, QEvent*) + 269
0x0000000108a52e0e QApplication::notify(QObject*, QEvent*) + 574
0x00000001096ee4b4 QCoreApplication::notifyInternal2(QObject*, QEvent*) + 212
0x00000001096ef6ae QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) + 878
0x000000010bdb44f9 0x10bd88000 + 181497
0x000000010bdb4d70 0x10bd88000 + 183664
0x00007fff4f9658f1 CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 17
0x00007fff4fa1f30c __CFRunLoopDoSource0 + 108
0x00007fff4f948350 __CFRunLoopDoSources0 + 208
0x00007fff4f9477cd __CFRunLoopRun + 1293
0x00007fff4f947033 CFRunLoopRunSpecific + 483
0x00007fff4ec31d96 RunCurrentEventLoopInMode + 286
0x00007fff4ec31a0f ReceiveNextEventCommon + 366
0x00007fff4ec31884 _BlockUntilNextEventMatchingListInModeWithFilter + 64
0x00007fff4cee1a73 _DPSNextEvent + 2085
0x00007fff4d677e34 -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 3044
0x00007fff4ced6885 -[NSApplication run] + 764
0x000000010bdb3c17 0x10bd88000 + 179223
0x00000001096e9b0f QEventLoop::exec(QFlagsQEventLoop::ProcessEventsFlag) + 431
0x00000001096eeac2 QCoreApplication::exec() + 130
0x0000000108a34b4d main + 61 (main.cpp:10)
0x00007fff77879015 start + 1

Thread 1:
0 libsystem_pthread.dylib 0x00007fff77b90bdc start_wqthread + 0
1 ??? 0x00000018000c0000 0 + 103080001536

Thread 2:
0 libsystem_kernel.dylib 0x00007fff779ca28a __workq_kernreturn + 10
1 libsystem_pthread.dylib 0x00007fff77b9120e _pthread_wqthread + 1552
2 libsystem_pthread.dylib 0x00007fff77b90be9 start_wqthread + 13

Thread 3:: Dispatch queue: NSCGSDisableUpdates
0 libsystem_kernel.dylib 0x00007fff779c020a mach_msg_trap + 10
1 libsystem_kernel.dylib 0x00007fff779bf724 mach_msg + 60
2 com.apple.SkyLight 0x00007fff7169d6a5 CGSUpdateManager::enable_updates_common() + 565
3 com.apple.SkyLight 0x00007fff71641828 CGSUpdateManager::enable_update(unsigned long long) + 320
4 libdispatch.dylib 0x00007fff778475fa _dispatch_call_block_and_release + 12
5 libdispatch.dylib 0x00007fff7783fdb8 _dispatch_client_callout + 8
6 libdispatch.dylib 0x00007fff77854217 _dispatch_queue_serial_drain + 635
7 libdispatch.dylib 0x00007fff77847166 _dispatch_queue_invoke + 373
8 libdispatch.dylib 0x00007fff77854f0d _dispatch_root_queue_drain_deferred_wlh + 332
9 libdispatch.dylib 0x00007fff77858d21 _dispatch_workloop_worker_thread + 880
10 libsystem_pthread.dylib 0x00007fff77b90fd2 _pthread_wqthread + 980
11 libsystem_pthread.dylib 0x00007fff77b90be9 start_wqthread + 13

Thread 4:
0 libsystem_kernel.dylib 0x00007fff779ca28a __workq_kernreturn + 10
1 libsystem_pthread.dylib 0x00007fff77b9120e _pthread_wqthread + 1552
2 libsystem_pthread.dylib 0x00007fff77b90be9 start_wqthread + 13

Thread 5:
0 libsystem_kernel.dylib 0x00007fff779ca28a __workq_kernreturn + 10
1 libsystem_pthread.dylib 0x00007fff77b9120e _pthread_wqthread + 1552
2 libsystem_pthread.dylib 0x00007fff77b90be9 start_wqthread + 13

Thread 6:: com.apple.NSEventThread
0 libsystem_kernel.dylib 0x00007fff779c020a mach_msg_trap + 10
1 libsystem_kernel.dylib 0x00007fff779bf724 mach_msg + 60
2 com.apple.CoreFoundation 0x00007fff4f948665 __CFRunLoopServiceMachPort + 341
3 com.apple.CoreFoundation 0x00007fff4f9479b7 __CFRunLoopRun + 1783
4 com.apple.CoreFoundation 0x00007fff4f947033 CFRunLoopRunSpecific + 483
5 com.apple.AppKit 0x00007fff4d01efc4 _NSEventThread + 184
6 libsystem_pthread.dylib 0x00007fff77b91661 _pthread_body + 340
7 libsystem_pthread.dylib 0x00007fff77b9150d _pthread_start + 377
8 libsystem_pthread.dylib 0x00007fff77b90bf9 thread_start + 13

Thread 0 crashed with X86 Thread State (64-bit):
rax: 0x0000000000000000 rbx: 0x00007fffb02bf380 rcx: 0x00007ffee71ccac8 rdx: 0x0000000000000000
rdi: 0x0000000000000307 rsi: 0x0000000000000006 rbp: 0x00007ffee71ccb00 rsp: 0x00007ffee71ccac8
r8: 0x0000000000000000 r9: 0x0000000000000000 r10: 0x0000000000000000 r11: 0x0000000000000206
r12: 0x0000000000000307 r13: 0x0000000000000004 r14: 0x0000000000000006 r15: 0x000000000000002d
rip: 0x00007fff779c9b66 rfl: 0x0000000000000206 cr2: 0x00007fffb029c168

The crash also occurred on Linux/Ubuntu OS.

aha_1980

@ThreeStones

MyDialog* dialog = new MyDialog(this);

With this you parent the dialog to your window, which will likely give a you double delete.

ThreeStones

@aha_1980 Thanks for your reply.

I just tried to remove "this", but it still crash at the same point. I got same backtrace call stack.

void
MainWindow::on_pushButton_clicked()
{
  MyDialog* dialog = new MyDialog();
  dialog->setAttribute(Qt::WA_DeleteOnClose,true);
  dialog->show();
}

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 libsystem_kernel.dylib 0x00007fff779c9b66 __pthread_kill + 10
1 libsystem_pthread.dylib 0x00007fff77b94080 pthread_kill + 333
2 libsystem_c.dylib 0x00007fff779251ae abort + 127
3 libsystem_malloc.dylib 0x00007fff77a23822 free + 521
4 org.qt-project.QtCore 0x000000010db622c2 QObject::event(QEvent*) + 146
5 org.qt-project.QtWidgets 0x000000010ced3798 QWidget::event(QEvent*) + 4776
6 org.qt-project.QtWidgets 0x000000010cfe3fa5 QMainWindow::event(QEvent*) + 277
7 org.qt-project.QtWidgets 0x000000010ce98a7d QApplicationPrivate::notify_helper(QObject*, QEvent*) + 269
8 org.qt-project.QtWidgets 0x000000010ce99e0e QApplication::notify(QObject*, QEvent*) + 574
9 org.qt-project.QtCore 0x000000010db394b4 QCoreApplication::notifyInternal2(QObject*, QEvent*) + 212
10 org.qt-project.QtCore 0x000000010db3a6ae QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) + 878
11 libqcocoa.dylib 0x00000001101b44f9 0x110188000 + 181497
12 libqcocoa.dylib 0x00000001101b4d70 0x110188000 + 183664
13 com.apple.CoreFoundation 0x00007fff4f9658f1 CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 17
14 com.apple.CoreFoundation 0x00007fff4fa1f30c __CFRunLoopDoSource0 + 108
15 com.apple.CoreFoundation 0x00007fff4f948350 __CFRunLoopDoSources0 + 208
16 com.apple.CoreFoundation 0x00007fff4f9477cd __CFRunLoopRun + 1293
17 com.apple.CoreFoundation 0x00007fff4f947033 CFRunLoopRunSpecific + 483
18 com.apple.HIToolbox 0x00007fff4ec31d96 RunCurrentEventLoopInMode + 286
19 com.apple.HIToolbox 0x00007fff4ec31a0f ReceiveNextEventCommon + 366
20 com.apple.HIToolbox 0x00007fff4ec31884 _BlockUntilNextEventMatchingListInModeWithFilter + 64
21 com.apple.AppKit 0x00007fff4cee1a73 _DPSNextEvent + 2085
22 com.apple.AppKit 0x00007fff4d677e34 -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 3044
23 com.apple.AppKit 0x00007fff4ced6885 -[NSApplication run] + 764
24 libqcocoa.dylib 0x00000001101b3c17 0x110188000 + 179223
25 org.qt-project.QtCore 0x000000010db34b0f QEventLoop::exec(QFlagsQEventLoop::ProcessEventsFlag) + 431
26 org.qt-project.QtCore 0x000000010db39ac2 QCoreApplication::exec() + 130
27 com.yourcompany.dialogtest 0x000000010ce7ab4d main + 61 (main.cpp:10)
28 libdyld.dylib 0x00007fff77879015 start + 1

aha_1980

@ThreeStones you are setting deleteOnClose on your main window, is that correct?

Are you closing the dialog or the main window?

ThreeStones

@aha_1980 Sorry I just correct the code. I am trying to delete the Dialog.

I am doing similar in a complicated application and observed same crash, so I just create a simple demo app.
If I change the code using connection signal/slot, it will not crash the application

LutDialog *lut = new  LutDialog(this);
//lut->setAttribute(Qt::WA_DeleteOnClose, true);
connect(lut, &LutDialog::destroyed, lut, &LutDialog::deleteLater);

This is the crash report for my real application.

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 org.qt-project.QtCore 0x0000000107298a58 QMetaObject::cast(QObject*) const + 24
1 org.qt-project.QtWidgets 0x000000010660ff4b QWidget::isActiveWindow() const + 283
2 org.qt-project.QtWidgets 0x000000010662039d QWidget::initPainter(QPainter*) const + 45
3 org.qt-project.QtGui 0x0000000106de00ed QPainter::begin(QPaintDevice*) + 781
4 org.qt-project.QtGui 0x0000000106ddfdd2 QPainter::QPainter(QPaintDevice*) + 242
5 org.qt-project.QtWidgets 0x0000000106613147 QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) + 2119
6 org.qt-project.QtWidgets 0x00000001065edcbb 0x1065d0000 + 122043
7 org.qt-project.QtWidgets 0x000000010661ab6a QWidget::event(QEvent*) + 1658
8 org.qt-project.QtWidgets 0x000000010672bfa5 QMainWindow::event(QEvent*) + 277
9 org.qt-project.QtWidgets 0x00000001065e0a7d QApplicationPrivate::notify_helper(QObject*, QEvent*) + 269
10 org.qt-project.QtWidgets 0x00000001065e1e0e QApplication::notify(QObject*, QEvent*) + 574
11 org.qt-project.QtCore 0x00000001072924b4 QCoreApplication::notifyInternal2(QObject*, QEvent*) + 212
12 org.qt-project.QtCore 0x00000001072936ae QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*)

ThreeStones

Found out what's wrong with my real application.

It is crashed due to this line of code in my main.cpp

QCoreApplication::setAttribute(Qt::AA_NativeWindows, true);

I dont know why this will crash the application :(. After removal of this code, tested many times in difference scenarios, the application worked very well.