perl crashed with SIGABRT in _dbus_abort()

Bug #1743216 reported by Carlos Gomes on 2018-01-14
This bug affects 27 people
Affects Status Importance Assigned to Milestone
perl (Ubuntu)
Status tracked in Cosmic
xdg-utils (Debian)
xdg-utils (Ubuntu)
Status tracked in Cosmic
Iain Lane
Iain Lane

Bug Description

[ Description ]

When xdg-screensaver suspend <wid> refers to a window with invalid UTF-8 in its title, it will spawn a perl process that crashes with an assertion:

  dbus[19455]: arguments to dbus_message_iter_append_basic() were incorrect, assertion "_dbus_check_is_valid_utf8 (*string_p)" failed in file ../../../dbus/dbus-message.c line 2754.
  This is normally a bug in some application using the D-Bus library.

[ Fix ]

Use decode() from the Encode module to replace invalid character sequences with U+FFFD, the replacement symbol. This is not a new dependency as Encode has been a perl core module since 5.8.

[ QA ]

I don't know how to get a window with such a title, so we can do two things.


1. $ sudo -e $(which xdg-screensaver) # hack the script
2. Find the line "# Inhibit idle detection (flags = 8) with window name and ID."
3. Find the } on its own above that. Insert a new line afterwards and set the window name to be the same as the one in this bug, by pasting the code
  $window_name = "\253\062\065 Meter fehlten bis zur Katastrophe\273 - News Panorama: Vermischtes - - Mozilla Firefox";
4. Save and exit
5. $ xwininfo
6. click some window, and copy the "Window id", which will be 0x<something>
7. $ xdg-screensaver suspend <that window id>

In the bad case (before this bug is fixed) it should crash, and in the good case it should work.

8. Undo what you just did by running $ xdg-screensaver resume <that window id>


Observe that the error bucket

has a reduction in report rate with the new versions.

[ Regression potential ]

If the code is bad then the window name passed to Inhibit() could be wrong. That shouldn't matter too much.

If it is really bad then the program might crash for everybody and we'll see an increase in errors.

[ Original description ]

Errors Bucket

crashed after launching the software updater

ProblemType: CrashDistroRelease: Ubuntu 18.04
Package: perl-base 5.26.1-4
ProcVersionSignature: Ubuntu 4.14.0-16.19-generic 4.14.12
Uname: Linux 4.14.0-16-generic x86_64
ApportVersion: 2.20.8-0ubuntu6
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sun Jan 14 13:30:52 2018
ExecutablePath: /usr/bin/perl
InstallationDate: Installed on 2017-12-28 (17 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20171201)
Signal: 6SourcePackage: perl
 _dbus_abort () from /lib/x86_64-linux-gnu/
 _dbus_warn_check_failed () from /lib/x86_64-linux-gnu/
 dbus_message_iter_append_basic () from /lib/x86_64-linux-gnu/
 ?? () from /usr/lib/x86_64-linux-gnu/perl5/5.26/auto/Net/DBus/
 Perl_pp_entersub ()
Title: perl crashed with SIGABRT in _dbus_abort()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin lxd plugdev sambashare sudo

Carlos Gomes (gocarlos) wrote :

 _dbus_abort () at ../../../dbus/dbus-sysdeps.c:93
 _dbus_warn_check_failed (format=format@entry=0x7f67696eb7c8 "arguments to %s() were incorrect, assertion \"%s\" failed in file %s line %d.\nThis is normally a bug in some application using the D-Bus library.\n") at ../../../dbus/dbus-internals.c:281
 _dbus_warn_return_if_fail (function=function@entry=0x7f67696ea1b0 <__func__.5319> "dbus_message_iter_append_basic", assertion=assertion@entry=0x7f67696e94b8 "_dbus_check_is_valid_utf8 (*string_p)", file=file@entry=0x7f67696e9a1d "../../../dbus/dbus-message.c", line=line@entry=2754) at ../../../dbus/dbus-internals.c:936
 dbus_message_iter_append_basic (iter=0x55e5b0ba6530, type=type@entry=115, value=value@entry=0x7ffd7fe845b0) at ../../../dbus/dbus-message.c:2754
 XS_Net__DBus__Binding__Iterator_append_string (my_perl=<optimized out>, cv=<optimized out>) at DBus.xs:1543

Changed in perl (Ubuntu):
importance: Undecided → Medium
tags: removed: need-amd64-retrace
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in perl (Ubuntu):
status: New → Confirmed
Brian Murray (brian-murray) wrote :

The ProcCmdline.txt file in this bug report, and some of its duplicates (I didn't check them all), are quite strange.

information type: Private → Public
Changed in perl (Ubuntu):
importance: Medium → High
description: updated
Brian Murray (brian-murray) wrote :

The perl code is actually from xdg-screensaver.

Changed in xdg-utils (Ubuntu):
status: New → Confirmed
importance: Undecided → High
tags: added: regression-release
removed: package-from-proposed
Changed in xdg-utils (Ubuntu):
assignee: nobody → Canonical Desktop Team (canonical-desktop-team)
tags: added: rls-cc-incoming
Will Cooke (willcooke) on 2018-09-25
Changed in xdg-utils (Ubuntu):
assignee: Canonical Desktop Team (canonical-desktop-team) → Iain Lane (laney)
tags: added: rls-cc-tracking
removed: rls-cc-incoming
Iain Lane (laney) on 2018-10-02
Changed in perl (Ubuntu Cosmic):
status: Confirmed → Invalid
Changed in xdg-utils (Ubuntu Bionic):
status: New → In Progress
assignee: nobody → Iain Lane (laney)
Iain Lane (laney) on 2018-10-02
description: updated
Iain Lane (laney) on 2018-10-02
description: updated
Iain Lane (laney) wrote :

OK, I think I understood it properly and these uploads (which are waiting in the queues currently) should fix it.

Changed in xdg-utils (Ubuntu Cosmic):
status: Confirmed → In Progress
affects: perl (Debian) → xdg-utils (Debian)
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package xdg-utils - 1.1.3-1ubuntu2

xdg-utils (1.1.3-1ubuntu2) cosmic; urgency=medium

  * Use perl's decode() to ensure we don't pass invalid UTF-8 to D-Bus, as
    doing so triggers an assertion from libdbus which makes us crash. LP:
    #1743216 (Debian #910070, Upstream #108121)

 -- Iain Lane <email address hidden> Tue, 02 Oct 2018 11:11:16 +0100

Changed in xdg-utils (Ubuntu Cosmic):
status: In Progress → Fix Released

Hello Carlos, or anyone else affected,

Accepted xdg-utils into bionic-proposed. The package will build now and be available at in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Changed in xdg-utils (Ubuntu Bionic):
status: In Progress → Fix Committed
tags: added: verification-needed verification-needed-bionic
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in perl (Ubuntu Bionic):
status: New → Confirmed
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