Ubuntu
lightdm package

Entering a ridiculously long login/password crashes lightdm

Bug #817186 reported by Jean-Baptiste Lallement
18
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Light Display Manager
Fix Released
High
Unassigned
lightdm (Ubuntu)
Fix Released
High
Unassigned

Bug Description

TEST CASE:
1. On the login screen, select an account
2. In the password field enter a very very long string (I entered 0123456789 repeated 100 times which is 1000 chars long)

Result:
The password field freezes (the UI is still working, but the password field is greyed, and never back to normal state) and this crash occurs.

ProblemType: Crash
DistroRelease: Ubuntu 11.10
Package: lightdm 0.9.2-0ubuntu3
ProcVersionSignature: Ubuntu 3.0.0-7.8-generic 3.0.0
Uname: Linux 3.0.0-7-generic i686
Architecture: i386
Date: Wed Jul 27 15:00:06 2011
Disassembly: => 0x390999: Cannot access memory at address 0x390999
ExecutablePath: /usr/sbin/lightdm
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha i386 (20110209)
ProcCmdline: lightdm
ProcEnviron: PATH=(custom, no user)
Signal: 5
SourcePackage: lightdm
Stacktrace:
 #0 0x00390999 in ?? ()
 No symbol table info available.
 Cannot access memory at address 0xbff447e0
StacktraceTop: ?? ()
Title: lightdm crashed with signal 5
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

mtime.conffile..etc.lightdm.lightdm.conf: 2011-07-25T23:56:44.233567

Revision history for this message
Jean-Baptiste Lallement (jibel) wrote :
Revision history for this message
Apport retracing service (apport) wrote :

Stacktrace:
 #0 0x00390999 in ?? ()
 No symbol table info available.
 Cannot access memory at address 0xbff447e0
StacktraceTop: ?? ()

Revision history for this message
Apport retracing service (apport) wrote : ThreadStacktrace.txt
Changed in lightdm (Ubuntu):
status: New → Invalid
Revision history for this message
Apport retracing service (apport) wrote : Crash report cannot be processed

Thank you for your report!

However, processing it in order to get sufficient information for the
developers failed (it does not generate an useful symbolic stack trace). This
might be caused by some outdated packages which were installed on your system
at the time of the report:

lightdm: installed version 0.9.2-0ubuntu3, latest version: 0.9.2-0ubuntu4

Please upgrade your system to the latest package versions. If you still
encounter the crash, please file a new report.

Thank you for your understanding, and sorry for the inconvenience!

tags: removed: need-i386-retrace
Revision history for this message
Jean-Baptiste Lallement (jibel) wrote : Re: Entering a ridiculously long password crashes lightdm

I'll try to get a better trace but the problem is still valid and reproducible. Setting back to new.

Changed in lightdm (Ubuntu):
status: Invalid → New
visibility: private → public
Jean-Baptiste Lallement (jibel)
summary: - Entering a ridiculously long password crashes lightdm
+ Entering a ridiculously long login/password crashes lightdm
Revision history for this message
Jean-Baptiste Lallement (jibel) wrote :

Here is the trace.

Sebastien Bacher (seb128)
Changed in lightdm (Ubuntu):
importance: Undecided → High
Ubuntu Foundations Team Bug Bot (crichton)
tags: added: testcase
Robert Ancell (robert-ancell)
Changed in lightdm (Ubuntu):
status: New → Fix Released
status: Fix Released → Triaged
Revision history for this message
Robert Ancell (robert-ancell) wrote :

Fixed in 1.0.2.

Changed in lightdm (Ubuntu):
status: Triaged → Fix Committed
Changed in lightdm:
status: New → Fix Committed
importance: Undecided → High
Robert Ancell (robert-ancell)
Changed in lightdm:
status: Fix Committed → Fix Released
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package lightdm - 1.0.1-0ubuntu4

---------------
lightdm (1.0.1-0ubuntu4) oneiric; urgency=low

  * debian/patches/04_language_not_to_LANG.patch:
  * debian/patches/04_dmrc_set_LANG_only.patch:
    - Replace LANG disabling code with proper fix (LP: #868149)
  * debian/patches/03_launch_dbus.patch:
  * debian/patches/05_gdmflexiserver_not_in_PATH.patch:
    - Refreshed
  * debian/patches/06_accounts_service_timeout.patch:
    - Fix D-Bus timeout when accounts service not installed (LP: #866035)
  * debian/patches/07_long_password_crash.patch:
    - Fix crash with long passwords (LP: #817186)
 -- Robert Ancell <email address hidden> Thu, 06 Oct 2011 15:45:21 +1100

Changed in lightdm (Ubuntu):
status: Fix Committed → Fix Released
Revision history for this message
Deckard (frank-s) wrote :

Sometimes my keyboard starts sending the number '5', as if someone is holding down the key. It stops if I touch another key.
If this happens while I'm away and the screen is locked, then I can't delete the password entry field or press enter to get an invalid password and start over. I can get a prompt via alt+ctrl+1 and sometimes it's enough to kill lightdm, and other times I must hold the power button down until the machine powers down, and make a cold boot. I know my keyboard is broken, but I don't think that it should kill the greeter.

Revision history for this message
Jakob Sloth Nielsen (jsloth) wrote :

I have the exact same issue as Deckard.
Using Ubuntu 15.10

Revision history for this message
Deckard (frank-s) wrote :

Update:

Sorry I forgot: Ubuntu 15.10, lightdm 1.16.7

Still the same problem as 2016-02-25:

Sometimes my keyboard starts sending the number '5', as if someone is holding down the key. It stops if I touch another key.
If this happens while I'm away and the screen is locked, then I can't delete the password entry field or press enter to get an invalid password and start over. I can get a prompt via alt+ctrl+1 and sometimes it's enough to kill lightdm, and other times I must hold the power button down until the machine powers down, and make a cold boot. I know my keyboard is broken, but I don't think that it should kill the greeter.

To post a comment you must log in.
This report contains Public information  
Everyone can see this information.
Subscribing...

Other bug subscribers

Remote bug watches

Bug watches keep track of this bug in other bug trackers.