qt5 apps crash on debian bullseye

[zanfix]

Hi all,

I am testing debian bullseye with Xserver XSDL and I noticed that any QT5 application will crash as soon you click on the application window.

There is an example for vlc:

zanf@localhost:~$ gdb vlc
GNU gdb (Debian 10.1-1.7) 10.1.90.20210103-git
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Reading symbols from vlc...
Reading symbols from /usr/lib/debug/.build-id/89/4240474f60635e726afe76d6cf824521ccb6f2.debug...
(gdb) run
Starting program: /usr/bin/vlc 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/aarch64-linux-gnu/libthread_db.so.1".
VLC media player 3.0.16 Vetinari (revision 3.0.13-8-g41878ff4f2)
[New Thread 0x7fbe53a140 (LWP 10792)]
[New Thread 0x7fbdd39140 (LWP 10793)]
[Thread 0x7fbdd39140 (LWP 10793) exited]
[New Thread 0x7fbd538140 (LWP 10794)]
[New Thread 0x7fbd414140 (LWP 10795)]
[000000555556a5c0] main libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
[New Thread 0x7fb10b2140 (LWP 10796)]
[New Thread 0x7fbdd39140 (LWP 10797)]
[New Thread 0x7fb0abd140 (LWP 10798)]
[New Thread 0x7fa6e89140 (LWP 10799)]
[New Thread 0x7fa6688140 (LWP 10800)]
[New Thread 0x7fa5d12140 (LWP 10801)]
[New Thread 0x7fa5511140 (LWP 10802)]
[New Thread 0x7fa4d10140 (LWP 10803)]
[New Thread 0x7f93fff140 (LWP 10804)]
[New Thread 0x7f937fe140 (LWP 10805)]
[New Thread 0x7fa43d3140 (LWP 10806)]
[New Thread 0x7f7b873140 (LWP 10807)]
[New Thread 0x7f7b072140 (LWP 10808)]
[New Thread 0x7f7a871140 (LWP 10809)]
[New Thread 0x7f7a070140 (LWP 10810)]
[New Thread 0x7f7986f140 (LWP 10811)]
[New Thread 0x7f7906e140 (LWP 10812)]
[New Thread 0x7f7886d140 (LWP 10813)]
[New Thread 0x7f5bfff140 (LWP 10814)]
[New Thread 0x7f5b7fe140 (LWP 10815)]
[New Thread 0x7f5affd140 (LWP 10816)]
[New Thread 0x7f5a7fc140 (LWP 10817)]
[New Thread 0x7f59ffb140 (LWP 10818)]
[New Thread 0x7f597fa140 (LWP 10819)]
[New Thread 0x7f58ff9140 (LWP 10820)]
[New Thread 0x7f43fff140 (LWP 10821)]
[New Thread 0x7f437fe140 (LWP 10822)]
[New Thread 0x7f42ffd140 (LWP 10823)]
[New Thread 0x7f427fc140 (LWP 10824)]
[New Thread 0x7f41ffb140 (LWP 10825)]
[New Thread 0x7f417fa140 (LWP 10826)]
[0000005555609650] main playlist: playlist is empty
qt.qpa.xcb: QXcbConnection: XCB error: 146 (Unknown), sequence: 191, resource id: 0, major code: 139 (Unknown), minor code: 20
qt.qpa.xcb: xcb_shm_create_segment() failed for size 504000

Thread 6 "vlc" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fb10b2140 (LWP 10796)]
0x0000007fbca0fac4 in QWidget::mapFromGlobal(QPoint const&) const () from /lib/aarch64-linux-gnu/libQt5Widgets.so.5
(gdb) bt
#0  0x0000007fbca0fac4 in QWidget::mapFromGlobal(QPoint const&) const () from /lib/aarch64-linux-gnu/libQt5Widgets.so.5
#1  0x0000007fbc9ea290 in QApplication::notify(QObject*, QEvent*) () from /lib/aarch64-linux-gnu/libQt5Widgets.so.5
#2  0x0000007fb3d51460 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib/aarch64-linux-gnu/libQt5Core.so.5
#3  0x0000007fbc9e7eb4 in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool, bool) ()
   from /lib/aarch64-linux-gnu/libQt5Widgets.so.5
#4  0x0000007fbca3b6b4 in ?? () from /lib/aarch64-linux-gnu/libQt5Widgets.so.5
#5  0x0000007fbca3e23c in ?? () from /lib/aarch64-linux-gnu/libQt5Widgets.so.5
#6  0x0000007fbc9e1a80 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib/aarch64-linux-gnu/libQt5Widgets.so.5
#7  0x0000007fb3d51460 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib/aarch64-linux-gnu/libQt5Core.so.5
#8  0x0000007fbc2f8d84 in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) () from /lib/aarch64-linux-gnu/libQt5Gui.so.5

Anybody is having this issue? Did somebody find a fix?

Does not happen with sparkle

Bye!

[zanfix]

I tried running vlc in Xephyr and it does not crash! it works!

[Lokawn]

Not only qt5 apps, LXQt doesn't even start.