gnome-settings-daemon crashed with SIGSEGV in g_unix_mount_get_mount_path()

Binary package hint: gnome-settings-daemon

Just after update to karmic.
Discovered a SMART error on System HD. System on LVM.

ProblemType: Crash
Architecture: amd64
Date: Wed Aug 26 19:30:38 2009
DistroRelease: Ubuntu 9.10
ExecutablePath: /usr/lib/gnome-settings-daemon/gnome-settings-daemon
LiveMediaBuild: Ubuntu 9.04 "Jaunty Jackalope" - Release amd64 (20090420.1)
Package: gnome-settings-daemon 2.27.90-0ubuntu1
ProcCmdline: /usr/lib/gnome-settings-daemon/gnome-settings-daemon
ProcEnviron:
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-7.27-generic
SegvAnalysis:
 Segfault happened at: 0x7f8fff15e749 <g_unix_mount_get_mount_path+9>: mov (%rdi),%rax
 PC (0x7f8fff15e749) ok
 source "(%rdi)" (0xab00000132) not located in a known VMA region (needed readable region)!
 destination "%rax" ok
SegvReason: reading unknown VMA
Signal: 11
SourcePackage: gnome-settings-daemon
StacktraceTop:
 g_unix_mount_get_mount_path ()
 ?? ()
 ?? () from /usr/lib/libglib-2.0.so.0
 g_main_context_dispatch ()
 ?? () from /usr/lib/libglib-2.0.so.0
Title: gnome-settings-daemon crashed with SIGSEGV in g_unix_mount_get_mount_path()
Uname: Linux 2.6.31-7-generic x86_64
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare

*** SRU stuff ***

The patch is located here: http://launchpadlibrarian.net/35063102/gnome-settings-daemon_2.28.1-0ubuntu2.debdiff

[Impact of bug]
gnome-settings-daemon will crash if you the volume is unmouned whilst a warning is displayed on screen, and then you click the "Examine" button.

[Description of change]
The change makes a copy of the path string returned from g_unix_mount_get_mount_path() before calling gtk_dialog_run(). The saved string is used when gtk_dialog_run() returns, rather than calling g_unix_mount_get_mount_path() on a GUnixMountEntry which might have been free'd if the volume was unmounted whilst in the main loop.

Care is taken to make sure that the copy of the string is not leaked

This will mean that baobab will open to an empty mount path if the user presses "Examine" on a volume that was just unmounted. Ideally, the low-disk space warning dialog will just disappear if the volume is unmounted whilst the warning is on screen, but a patch to implement this would be much more intrusive (and is something I will pursue separately upstream, but would not really be suitable for a SRU). This patch just stops gnome-settings-daemon from crashing.

[Test case]
To test, you need to trigger the low-disk space warning on a mount that is listed in /etc/fstab, and can be unmounted without affecting the rest of the system. To artificially trigger the low disk-space warning, adjust the thresholds in /apps/gnome_settings_daemon/housekeeping.

Test 2.28.1-0ubuntu1 and 2.28.1-0ubuntu2 in turn.

When the low disk-space warning for the particular mount is displayed on screen:
1) Unmount the volume
2) Press the "Examine" button.

With the old version, gnome-settings-daemon will crash at step 2. With the new version of gnome-settings-daemon, baobab will open successfully (albeit, pointing to a now empty folder)

[Regression potential]
None - the code change is fairly minimal and self-contained.