** Description changed: - Last time I hacked around a bug like this, it had portions in PAM, - apparmor, Seahorse, and Gnome so this time I'd like someone more focused - on broad stability to look at things. + [ Impact ] - The problem is simple. Before the upgrade to 23.10, I could log in - using the "Ubuntu", "Ubuntu on X.org". "Gnome", and "Gnome on X.org" - WMs. Now I can't. I can still login using XFCE and TTY. + gnome-shell may crash on startup due to multiple threads writing and + reading environment variables. + + gnome-shell adds variables like DISPLAY, XAUTHORITY, WAYLAND_DISPLAY to + its own environment. However it might do so while libraries running in + other threads are trying to read environment variables that may affect + their behaviour. If a call to `getenv` is interrupted by a call to + `setenv` that causes re-allocation of memory, it will trigger a crash. + + To mitigate the issue, we avoid starting the fontconfig thread right + before setting the environment variables. + + [ Test Plan ] + + There are no reproducer steps that trigger the crash reliably enough to be verified. + Instead, we are going to verify that the patch does not introduce regressions, and will verify the effectiveness of the fix by monitoring errors.ubuntu.com after the update has landed. + + 1. Install the gnome-shell update + 2. Reboot + 3. Verify that the log-in screen loaded correctly + 4. Log-in + 5. Verify that the desktop loaded correctly + 6. Verify that the font rendering quality is not degraded + + [ Where problems could occur ] + + The patch delays the disablement of text mipmapping to the first time a + font is rendered, instead of doing so on startup. A mistake in the patch + could thus affect font rendering. The test plan asks to verify that that + is not the case.
-- You received this bug notification because you are a member of Desktop Packages, which is subscribed to gnome-shell in Ubuntu. https://bugs.launchpad.net/bugs/2039340 Title: gnome-shell (login screen) crashes with SIGSEGV in __GI_getenv("EXPAT_ACCOUNTING_DEBUG") from getDebugLevel() from parserInit() Status in Mutter: New Status in gnome-shell package in Ubuntu: Fix Released Status in gnome-shell source package in Noble: In Progress Bug description: [ Impact ] gnome-shell may crash on startup due to multiple threads writing and reading environment variables. gnome-shell adds variables like DISPLAY, XAUTHORITY, WAYLAND_DISPLAY to its own environment. However it might do so while libraries running in other threads are trying to read environment variables that may affect their behaviour. If a call to `getenv` is interrupted by a call to `setenv` that causes re-allocation of memory, it will trigger a crash. To mitigate the issue, we avoid starting the fontconfig thread right before setting the environment variables. [ Test Plan ] There are no reproducer steps that trigger the crash reliably enough to be verified. Instead, we are going to verify that the patch does not introduce regressions, and will verify the effectiveness of the fix by monitoring errors.ubuntu.com after the update has landed. 1. Install the gnome-shell update 2. Reboot 3. Verify that the log-in screen loaded correctly 4. Log-in 5. Verify that the desktop loaded correctly 6. Verify that the font rendering quality is not degraded [ Where problems could occur ] The patch delays the disablement of text mipmapping to the first time a font is rendered, instead of doing so on startup. A mistake in the patch could thus affect font rendering. The test plan asks to verify that that is not the case. To manage notifications about this bug go to: https://bugs.launchpad.net/mutter/+bug/2039340/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
