Investigated this, it is due to the theming code failing to get a settings object, probably due to the shell not running at the time. The GTK functions that return the settings object are allowed to return NULL, and this case was not being handled in GTK. The attached patch contains three fixes in GTK to handle these cases. These cases were found by forcing the settings object to be NULL and then running a test program and fixing the segfaults.
** Patch added: "fix-no-shell.patch" https://bugs.launchpad.net/ubuntu/+source/apport/+bug/1842439/+attachment/5629117/+files/fix-no-shell.patch -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apport in Ubuntu. https://bugs.launchpad.net/bugs/1842439 Title: apport-gtk crashed with SIGSEGV in _gtk_settings_get_screen(settings=0x0) from gtk_css_value_icon_theme_compute() from gtk_css_static_style_compute_value() Status in apport package in Ubuntu: Triaged Status in gtk+3.0 package in Ubuntu: Confirmed Status in apport source package in Focal: Triaged Status in gtk+3.0 source package in Focal: Confirmed Bug description: Steps to reproduce ------------------ 1. Use GNOME with GNOME shell 2. killall -11 gnome-shell Suspicious Apport log: gdbus call error: Error: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files Error tracker ------------- https://errors.ubuntu.com/problem/815a179408135a894bbb5921adef3757563c75c5 https://errors.ubuntu.com/problem/276759c7bf0b6628977c63ca70d26b53c9defd22 Original report --------------- Session suddenly stopped and came back to login screen, all opened windows lost. ProblemType: Crash DistroRelease: Ubuntu 19.10 Package: apport-gtk 2.20.11-0ubuntu7 ProcVersionSignature: Ubuntu 5.2.0-15.16-generic 5.2.9 Uname: Linux 5.2.0-15-generic x86_64 ApportVersion: 2.20.11-0ubuntu7 Architecture: amd64 CrashReports: 640:1000:117:7292709:2019-09-03 16:20:13.909392833 +0200:2019-09-03 16:20:14.909392833 +0200:/var/crash/_usr_share_apport_apport-gtk.1000.crash 640:1000:117:48937942:2019-09-03 16:20:11.681426286 +0200:2019-09-03 16:20:12.681426286 +0200:/var/crash/_usr_bin_gnome-shell.1000.crash 640:1000:117:32054:2019-08-27 17:39:07.125607490 +0200:2019-08-28 12:36:17.087672961 +0200:/var/crash/_usr_bin_dbus-daemon.1000.crash CurrentDesktop: ubuntu:GNOME Date: Tue Sep 3 16:20:13 2019 ExecutablePath: /usr/share/apport/apport-gtk InstallationDate: Installed on 2018-06-16 (443 days ago) InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Alpha amd64 (20180611) InterpreterPath: /usr/bin/python3.7 PackageArchitecture: all ProcCmdline: /usr/bin/python3 /usr/share/apport/apport-gtk ProcEnviron: PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=fr_FR.UTF-8 SHELL=/bin/bash Python3Details: /usr/bin/python3.7, Python 3.7.4, python3-minimal, 3.7.3-1 PythonDetails: /usr/bin/python2.7, Python 2.7.16+, python-minimal, 2.7.16-1 SegvAnalysis: Segfault happened at: 0x7f532548f8c4: mov 0x18(%rdi),%rax PC (0x7f532548f8c4) ok source "0x18(%rdi)" (0x00000018) not located in a known VMA region (needed readable region)! destination "%rax" ok SegvReason: reading NULL VMA Signal: 11 SourcePackage: apport StacktraceTop: ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0 ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0 ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0 ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0 ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0 Title: apport-gtk crashed with SIGSEGV UpgradeStatus: Upgraded to eoan on 2019-06-10 (84 days ago) UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo separator: To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apport/+bug/1842439/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
