The VM sometimes crashes with SEGV when the host blanks the screen on idle or the screen is locked.
Host: Arch (Kernel 6.14.9-arch1-1), Gnome+Wayland, Ryzen 9900X, RX 9070 XT, VirtualBox 7.1.8 r168469, all updates applied
Guest: Ubuntu 20.04 (Kernel: 5.15.0-139-generic)
PID: 115549 (VirtualBoxVM)
UID: 1000 (user)
GID: 1000 (user)
Signal: 11 (SEGV)
Timestamp: Mon 2025-06-02 17:17:07 CEST (37min ago)
Command Line: /usr/lib/virtualbox/VirtualBoxVM --comment Ubuntu --startvm [...] --no-startvm-errormsgbox
Executable: /usr/lib/virtualbox/VirtualBoxVM
Control Group: /user.slice/user-1000.slice/user@1000.service/app.slice/app-gnome-virtualbox-115467.scope
Unit: user@1000.service
User Unit: app-gnome-virtualbox-115467.scope
Slice: user-1000.slice
Owner UID: 1000 (user)
Boot ID: [...]
Machine ID: [...]
Hostname: computer
Storage: /var/lib/systemd/coredump/core.VirtualBoxVM.1000.[...].115549.1748877427000000.zst (present)
Size on Disk: 27.2M
Message: Process 115549 (VirtualBoxVM) of user 1000 dumped core.
Stack trace of thread 115549:
#0 0x00007f38d3bd8b58 _ZNK17QAccessibleWidget4textEN11QAccessible4TextE (libQt6Widgets.so.6 + 0x3d8b58)
#1 0x00007f38d393ea6c _ZN14QWidgetPrivate18setWindowTitle_sysERK7QString (libQt6Widgets.so.6 + 0x13ea6c)
#2 0x00007f38d393f4a2 _ZN14QWidgetPrivate21setWindowTitle_helperERK7QString (libQt6Widgets.so.6 + 0x13f4a2)
#3 0x00007f38d3955b90 _ZN14QWidgetPrivate24setWindowModified_helperEv (libQt6Widgets.so.6 + 0x155b90)
#4 0x00007f38d393ce0f _ZN14QWidgetPrivate6createEv (libQt6Widgets.so.6 + 0x13ce0f)
#5 0x00007f38d393bdf6 _ZN7QWidget6createEybb (libQt6Widgets.so.6 + 0x13bdf6)
#6 0x00007f38d39407f9 _ZN7QWidget14setWindowStateE6QFlagsIN2Qt11WindowStateEE (libQt6Widgets.so.6 + 0x1407f9)
#7 0x00007f38d3940a3b _ZN7QWidget13showMaximizedEv (libQt6Widgets.so.6 + 0x140a3b)
#8 0x00007f38d995d458 _ZN23UIDesktopWidgetWatchdog34sltHandleHostScreenWorkAreaResizedERK5QRect (UICommon.so + 0x35d458)
#9 0x00007f38d8fb6cc9 n/a (libQt6Core.so.6 + 0x1b6cc9)
#10 0x00007f38d85e435a n/a (libQt6Gui.so.6 + 0x1e435a)
#11 0x00007f38d859b7d9 _ZN22QGuiApplicationPrivate27processScreenGeometryChangeEPN29QWindowSystemInterfacePrivate19ScreenGeometryEventE (libQt6Gui.so.6 + 0x19b7d9)
#12 0x00007f38d860d0c4 _ZN22QWindowSystemInterface22sendWindowSystemEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt6Gui.so.6 + 0x20d0c4)
#13 0x00007f38d3054d67 n/a (libQt6XcbQpa.so.6 + 0x53d67)
#14 0x00007f38d830887d n/a (libglib-2.0.so.0 + 0x5e87d)
#15 0x00007f38d8309cd7 n/a (libglib-2.0.so.0 + 0x5fcd7)
#16 0x00007f38d8309ee5 g_main_context_iteration (libglib-2.0.so.0 + 0x5fee5)
#17 0x00007f38d91cd59d _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt6Core.so.6 + 0x3cd59d)
#18 0x00007f38d8f65376 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt6Core.so.6 + 0x165376)
#19 0x00007f38d8f5d159 _ZN16QCoreApplication4execEv (libQt6Core.so.6 + 0x15d159)
#20 0x00007f38db4dd1ff TrustedMain (VirtualBoxVM.so + 0x5b1ff)
#21 0x00007f38e00d06b5 n/a (libc.so.6 + 0x276b5)
#22 0x00007f38e00d0769 __libc_start_main (libc.so.6 + 0x27769)
#23 0x00005600f70142d5 n/a (/usr/lib/virtualbox/VirtualBoxVM + 0x32d5)
EDIT: Reproducible with Gnome plugin "Fullscreen Avoider". The plugin moves the top bar of Gnome to another screen when an application enters full screen. On screen lock the VM loses fullscreen status, the top bar returns to the main screen and resizes the client area at the same moment the screen blanks.
The VM sometimes crashes with SEGV when the host blanks the screen on idle or the screen is locked.
Host: Arch (Kernel 6.14.9-arch1-1), Gnome+Wayland, Ryzen 9900X, RX 9070 XT, VirtualBox 7.1.8 r168469, all updates applied
Guest: Ubuntu 20.04 (Kernel: 5.15.0-139-generic)
EDIT: Reproducible with Gnome plugin "Fullscreen Avoider". The plugin moves the top bar of Gnome to another screen when an application enters full screen. On screen lock the VM loses fullscreen status, the top bar returns to the main screen and resizes the client area at the same moment the screen blanks.