Program crashes at QApplication::exec()

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29th January 2017, 00:00
lugarci2

Program crashes at QApplication::exec()

I've been making a little program in a 32 bit machine, and later i tried to compile it on a 64 bit machine (debian testing up-to-date). I thought it should compile and work fine, as i don't use anything 32bit-specific thing. The program compiled and run very well on the 32 bit computer, and compiles fine on the 64 bit computer, but it crashes unexpectedly. I can run the program for a few seconds, and later it crashes. It uses a QAbstractTableModel. When i try to use the debugger, it crashes without even being able to use the program, on the QApplication::exec() function.

Here is the backtrace:

Quote:

*** Error in `/home/user404/Desarrollo/build-LittleProgram-Desktop-Debug/LittleProgram': free(): invalid pointer: 0x00007fffffffb3e8 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x70bcb)[0x7ffff5e12bcb]
/lib/x86_64-linux-gnu/libc.so.6(+0x76fa6)[0x7ffff5e18fa6]
/lib/x86_64-linux-gnu/libc.so.6(+0x7779e)[0x7ffff5e1979e]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(+0x1b0d28)[0x7ffff6da9d28]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZNK19QStyledItemDelegate15initStyle OptionEP20QStyleOptionViewItemRK11QModelIndex+0xed )[0x7ffff788f6bd]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZNK19QStyledItemDelegate5paintEP8QP ainterRK20QStyleOptionViewItemRK11QModelIndex+0x4f )[0x7ffff788eaef]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(+0x729a74)[0x7ffff7815a74]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN10QTableView10paintEventEP11QPain tEvent+0x89a)[0x7ffff781f92a]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN7QWidget5eventEP6QEvent+0x290)[0x7ffff7306e80]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN6QFrame5eventEP6QEvent+0x1e)[0x7ffff76cbc8e]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN17QAbstractItemView13viewportEven tEP6QEvent+0x1e3)[0x7ffff77f0ba3]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(_ZN23QCoreApplicationPrivate29sendT hroughObjectEventFiltersEP7QObjectP6QEvent+0x91)[0x7ffff6d840a1]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN19QApplicationPrivate13notify_hel perEP7QObjectP6QEvent+0x6c)[0x7ffff72b052c]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN12QApplication6notifyEP7QObjectP6 QEvent+0x2cc)[0x7ffff72b752c]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(_ZN16QCoreApplication14notifyIntern alEP7QObjectP6QEvent+0x8d)[0x7ffff6d83f1d]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate10drawWidgetEP12Q PaintDeviceRK7QRegionRK6QPointiP8QPainterP19QWidge tBackingStore+0x605)[0x7ffff73014e5]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x45 8)[0x7ffff7301ed8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate10drawWidgetEP12Q PaintDeviceRK7QRegionRK6QPointiP8QPainterP19QWidge tBackingStore+0x196)[0x7ffff7301076]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x45 8)[0x7ffff7301ed8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate10drawWidgetEP12Q PaintDeviceRK7QRegionRK6QPointiP8QPainterP19QWidge tBackingStore+0x196)[0x7ffff7301076]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x45 8)[0x7ffff7301ed8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate10drawWidgetEP12Q PaintDeviceRK7QRegionRK6QPointiP8QPainterP19QWidge tBackingStore+0x196)[0x7ffff7301076]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x45 8)[0x7ffff7301ed8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x35 8)[0x7ffff7301dd8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate10drawWidgetEP12Q PaintDeviceRK7QRegionRK6QPointiP8QPainterP19QWidge tBackingStore+0x196)[0x7ffff7301076]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate22paintSiblingsRe cursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QReg ionRK6QPointiP8QPainterP19QWidgetBackingStore+0x45 8)[0x7ffff7301ed8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN14QWidgetPrivate10drawWidgetEP12Q PaintDeviceRK7QRegionRK6QPointiP8QPainterP19QWidge tBackingStore+0x196)[0x7ffff7301076]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(+0x3e564a)[0x7ffff74d164a]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(+0x3e59e3)[0x7ffff74d19e3]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(+0x236cb8)[0x7ffff7322cb8]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(_ZN12QApplication15x11ProcessEventEP 7_XEvent+0xebe)[0x7ffff7330d7e]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(+0x26e502)[0x7ffff735a502]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_dispatch+0x2a7)[0x7ffff56807f7]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x4aa60)[0x7ffff5680a60]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_iteration+0x2c)[0x7ffff5680b0c]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(_ZN20QEventDispatcherGlib13processE ventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE+0 x64)[0x7ffff6db4854]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(+0x26e5d6)[0x7ffff735a5d6]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(_ZN10QEventLoop13processEventsE6QFl agsINS_17ProcessEventsFlagEE+0x3f)[0x7ffff6d827ef]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(_ZN10QEventLoop4execE6QFlagsINS_17P rocessEventsFlagEE+0x1b5)[0x7ffff6d82b55]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(_ZN16QCoreApplication4execEv+0x99)[0x7ffff6d88bd9]
/home/user404/Desarrollo/build-LittleProgram-Desktop-Debug/LittleProgram(+0x60c5)[0x55555555a0c5]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf1)[0x7ffff5dc22b1]
/home/user404/Desarrollo/build-LittleProgram-Desktop-Debug/LittleProgram(+0x5f2a)[0x555555559f2a]

It seems that im missing some debian package for debugging symbols?, but the crash seems a mistery for me right now... :confused:
30th January 2017, 09:42
anda_skoa

Re: Program crashes at QApplication::exec()

Best way forward is to run a reduced program, e.g. with code commented out, and see when starts/stops crashing.

Since you mention a model try not creating and instantiating the model, i.e. having an empty view.

Cheers,
_
30th January 2017, 10:40
high_flyer

Re: Program crashes at QApplication::exec()

In addition you can simply run it with a debugger, it will probably show you the crashing line and stop execution with the call stack still visible.
Then you can look in the call stack which is the last line in your code - that is the offending line.

Re: Program crashes at QApplication::exec()

Quote:

Best way forward is to run a reduced program, e.g. with code commented out, and see when starts/stops crashing.

Since you mention a model try not creating and instantiating the model, i.e. having an empty view.

Cheers,

Yes, i forgot to mention that the model loads data from a file, and that if the file isn't there, that is, the model is empty, the program runs fine. I tried commenting code out, and just give static numbers from the model, but it also crashes. And what it surprises me, is that the rows with those static numbers also have a checkbox. The same happens when the real data is there, and if i select the row, it crashes, altough i don't handle selection in my code. Another thing, is that the first time the program at least shows up, i can see the data, and later it crashes, but later when i try to run it again, it crashes before i can see anything.

Quote:

In addition you can simply run it with a debugger, it will probably show you the crashing line and stop execution with the call stack still visible.
Then you can look in the call stack which is the last line in your code - that is the offending line.

The offending line is in my main function, when i call QApplication::exec(), here is the call stack (i had to put it as CODE):

Code:

1  __GI_raise                                             raise.c                      58   
2  __GI_abort                                             abort.c                      89   
3  __libc_message                                         libc_fatal.c                 175  
4  malloc_printerr                                        malloc.c                     5046 
5  _int_free                                              malloc.c                     3902 
6  clear                                                  qvariant.cpp                 291  
7  QStyledItemDelegate::initStyleOption                   qstyleditemdelegate.cpp      333  
8  QStyledItemDelegate::paint                             qstyleditemdelegate.cpp      425  
9  QTableViewPrivate::drawCell                            qtableview.cpp               929  
10 QTableView::paintEvent                                 qtableview.cpp               1419 
11 QWidget::event                                         qwidget.cpp                  8775 
12 QFrame::event                                          qframe.cpp                   557  
13 QAbstractItemView::viewportEvent                       qabstractitemview.cpp        1644 
14 QCoreApplicationPrivate::sendThroughObjectEventFilters qcoreapplication.cpp         1065 
15 QApplicationPrivate::notify_helper                     qapplication.cpp             4566 
16 QApplication::notify                                   qapplication.cpp             4356 
17 QCoreApplication::notifyInternal                       qcoreapplication.cpp         955  
18 QCoreApplication::sendSpontaneousEvent                 qcoreapplication.h           234  
19 QWidgetPrivate::drawWidget                             qwidget.cpp                  5599 
20 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5808 
21 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
22 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
23 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
24 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
25 QWidgetPrivate::drawWidget                             qwidget.cpp                  5652 
26 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5808 
27 QWidgetPrivate::drawWidget                             qwidget.cpp                  5652 
28 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5808 
29 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
30 QWidgetPrivate::drawWidget                             qwidget.cpp                  5652 
31 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5808 
32 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
33 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
34 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
35 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
36 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5795 
37 QWidgetPrivate::drawWidget                             qwidget.cpp                  5652 
38 QWidgetPrivate::paintSiblingsRecursive                 qwidget.cpp                  5808 
39 QWidgetPrivate::drawWidget                             qwidget.cpp                  5652 
40 QWidgetBackingStore::sync                              qbackingstore.cpp            1373 
41 QWidgetBackingStore::sync                              qbackingstore.cpp            1161 
42 QWidgetPrivate::syncBackingStore                       qwidget.cpp                  1903 
43 QETWidget::translatePaintEvent                         qapplication_x11.cpp         5277 
44 QApplication::x11ProcessEvent                          qapplication_x11.cpp         3574 
45 x11EventSourceDispatch                                 qguieventdispatcher_glib.cpp 146  
46 g_main_dispatch                                        gmain.c                      3203 
47 g_main_context_dispatch                                gmain.c                      3856
48 g_main_context_iterate                                 gmain.c                      3929 
49 g_main_context_iteration                               gmain.c                      3990 
50 QEventDispatcherGlib::processEvents                    qeventdispatcher_glib.cpp    425  
51 QGuiEventDispatcherGlib::processEvents                 qguieventdispatcher_glib.cpp 204  
52 QEventLoop::processEvents                              qeventloop.cpp               149   
53 QEventLoop::exec                                       qeventloop.cpp               204   
54 QCoreApplication::exec                                 qcoreapplication.cpp         
55 main                                                   main.cpp

And in the program output, i get: "free(): invalid pointer: 0x00007fffffffb518". I use a QList private data member in the model to store the data from the file, maybe it has something to do with this?, but again, i tried to not load data from the file, and just give numbers from the model, maybe i'm doing something wrong, i will keep checking...

Thank you for your answers!

30th January 2017, 20:25
d_stranz

Re: Program crashes at QApplication::exec()

It might help if you actually posted some code instead of just stack dumps, and reduced your code to something that reproduces the problem.

Quote:

I use a QList private data member in the model to store the data from the file, maybe it has something to do with this?

I'd say that was a pretty good bet.
31st January 2017, 18:05
lugarci2

Re: Program crashes at QApplication::exec()
I've found the problem, a really silly thing, i didn't return an invalid QVariant in the data() function of the model if it was another role different than DisplayRole. But i wonder why it worked fine in 32 bits... :confused:
Code:

QVariant TableModel::data(const QModelIndex &index, int role) const { if (role == Qt::DisplayRole){ ... } return QVariant(); //I missed this }
Anyway, again, thanks for your answers!
1st February 2017, 06:59
Lesiok

Re: Program crashes at QApplication::exec()

Strange compiler settings - should be an error message.
1st February 2017, 09:20
anda_skoa

Re: Program crashes at QApplication::exec()

Quote:

Originally Posted by lugarci2

I've found the problem, a really silly thing, i didn't return an invalid QVariant in the data() function of the model if it was another role different than DisplayRole.

Ah, yes, that was at least one obvious error when you said you are seeing checkboxes.

Cheers,
_
1st February 2017, 14:11
lugarci2

Re: Program crashes at QApplication::exec()

Quote:

Originally Posted by Lesiok

Strange compiler settings - should be an error message.

Mmmm, i have gcc default, and qmake with these arguments: "-r -spec linux-g++-64 CONFIG+=debug", also default.