Bug 358125

Summary: the lock-up can be pass through without typing password
Product: [Plasma] kscreenlocker Reporter: Nils <bugs.kde.org.trustful938>
Component: generalAssignee: Plasma Bugs List <plasma-bugs>
Status: RESOLVED FIXED    
Severity: major CC: bhush94, kde, mgraesslin, plasma-bugs, rdieter
Priority: NOR    
Version: unspecified   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: http://commits.kde.org/kscreenlocker/fae65f1cdd6446042b31ccd0eafd7a4c0b6623e3 Version Fixed In: 5.5.5
Sentry Crash Report:
Attachments: errors when logging for the first time
Hacking KDE session locker by closing the lid several times

Description Nils 2016-01-17 14:48:03 UTC 
When I let my computer idle for some time, it automatically lock-up, and it used to be then impossible to use  my computer without knowing my password.

However, I have found a trick which allow me to open the session without typing any password. 
With my laptop, I first connect my HDMI output to a second screen, then I am waiting for the idle lock-up to occurs. When it is really locked (not immediately after the lock-up appears but something like one minute after) I just have to close the lid and my session is instantaneously reopen without typing anything.
Also, the panel disappear in the operation.  

Reproducible: Always

Steps to Reproduce:
1. Use a laptop
2. Use a second screen through HDMI
3. Wait for an automatically closed session
4. Then close the lid

Actual Results:  
The session is unlocked

Expected Results:  
The session should still be locked

I am not sure which severity I should choose, and I don't know whether it is reproducible on another computer. However it seems really serious and not much reassuring.
Comment 1 David Edmundson 2016-01-17 19:06:28 UTC 
Thanks

Under screen locking (system settings -> desktop behaviour -> screen locking) there is an option 

"Require password after []" . During which if you wiggle the mouse everything unlocks without the password. Are you closing the laptop lid within that time?
Comment 2 Nils 2016-01-18 08:32:37 UTC 
The time indicated is 5 secondes. I have been thinking that first, but when I try to wiggle the mouse, it does not unlock. Furthermore, the time during which I do nothing is greater than 5 minutes & 5 secondes (I have not updated these settings).

It is only by closing the lid that I can unlock my session. 

Another thing really strange (but not sure whether related). When opening for the first time my session (following a reboot), I need to type several time my password (rightly). Each time it makes all the SDDM disappears and reboot it. Until... somehow... it finish by opening my session. 
When I type the bad password it is flag as bad... but when right typed, it just seems to crash. 

You will find some errors logs on the attached file.
Comment 3 Nils 2016-01-18 08:33:32 UTC 
Created attachment 96706 [details]
errors when logging for the first time
Comment 4 David Edmundson 2016-01-20 18:32:05 UTC 
Tested here, I can't reproduce. 

That SDDM bug is tracked on another bug.
Comment 5 Nils 2016-01-20 18:49:00 UTC 
Created attachment 96755 [details]
Hacking KDE session locker by closing the lid several times

So here the full log about my successful KDE hacking by closing the lid. :)
Comment 6 Nils 2016-01-20 18:52:07 UTC 
@David Edmundson, 

So I have tested it again on my updated computer and it has not been long before I have been successfully logged in as root on my computer without typing any password by just closing the lid several times. 
The people outside looked me like I was crazy. :D

Cheers,
Comment 7 Martin Flöser 2016-01-20 22:52:29 UTC 
Do you have configured your system with a user password?
Comment 8 Nils 2016-01-20 22:59:56 UTC 
Yes for all the users.
Comment 9 Nils 2016-02-03 13:23:28 UTC 
Well, I tried again with the last updates:
[2016-01-22 15:36] [ALPM] upgraded linux (4.3.3-2 -> 4.3.3-3)
[2016-01-22 15:36] [ALPM] upgraded plasma-framework (5.18.0-1 -> 5.18.0-3)
[2016-01-27 13:51] [ALPM] upgraded kde-cli-tools (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded kde-gtk-config (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded kdecoration (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded breeze (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded libksysguard (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded libkscreen (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded plasma-workspace (5.5.3-2 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded kdeplasma-addons (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded kinfocenter (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded kmenuedit (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded kscreen (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded ksshaskpass (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded ksysguard (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded kwrited (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded plasma-desktop (5.5.3-2 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded plasma-nm (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded plasma-pa (5.5.3-1 -> 5.5.4-1)
[2016-01-27 13:51] [ALPM] upgraded plasma-workspace-wallpapers (5.5.3-1 -> 5.5.4-1)

And I am still facing the issue, below the automated crash error reporter logs:
Application: Plasma (plasmashell), signal: Segmentation fault
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fb8fffe2800 (LWP 1862))]

Thread 14 (Thread 0x7fb8e882c700 (LWP 1879)):
#0  0x00007fb8fa61416d in read () from /usr/lib/libc.so.6
#1  0x00007fb8f75d5270 in ?? () from /usr/lib/libglib-2.0.so.0
#2  0x00007fb8f7591aa4 in g_main_context_check () from /usr/lib/libglib-2.0.so.0
#3  0x00007fb8f7591f60 in ?? () from /usr/lib/libglib-2.0.so.0
#4  0x00007fb8f75920cc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#5  0x00007fb8faf3b56b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#6  0x00007fb8faee257a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#7  0x00007fb8facfebe4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#8  0x00007fb8fd617055 in ?? () from /usr/lib/libQt5Qml.so.5
#9  0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#10 0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#11 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 13 (Thread 0x7fb8e0f7b700 (LWP 1884)):
#0  0x00007fb8f75d6614 in g_mutex_unlock () from /usr/lib/libglib-2.0.so.0
#1  0x00007fb8f7591e6d in ?? () from /usr/lib/libglib-2.0.so.0
#2  0x00007fb8f75920cc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#3  0x00007fb8faf3b56b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#4  0x00007fb8faee257a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#5  0x00007fb8facfebe4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#6  0x00007fb8fd617055 in ?? () from /usr/lib/libQt5Qml.so.5
#7  0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#8  0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#9  0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 12 (Thread 0x7fb8da495700 (LWP 1893)):
#0  0x00007fb8f75d65f9 in g_mutex_lock () from /usr/lib/libglib-2.0.so.0
#1  0x00007fb8f7591b46 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#2  0x00007fb8f7592020 in ?? () from /usr/lib/libglib-2.0.so.0
#3  0x00007fb8f75920cc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#4  0x00007fb8faf3b56b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#5  0x00007fb8faee257a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#6  0x00007fb8facfebe4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#7  0x00007fb8fd617055 in ?? () from /usr/lib/libQt5Qml.so.5
#8  0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#9  0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#10 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 11 (Thread 0x7fb8d8b7f700 (LWP 1902)):
#0  0x00007fb8f9e2607f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fb8ffa3f934 in ?? () from /usr/lib/libQt5Script.so.5
#2  0x00007fb8ffa3f979 in ?? () from /usr/lib/libQt5Script.so.5
#3  0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#4  0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 10 (Thread 0x7fb8d2161700 (LWP 1905)):
#0  0x00007fb8f75d65f9 in g_mutex_lock () from /usr/lib/libglib-2.0.so.0
#1  0x00007fb8f7591b46 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#2  0x00007fb8f7592020 in ?? () from /usr/lib/libglib-2.0.so.0
#3  0x00007fb8f75920cc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#4  0x00007fb8faf3b56b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#5  0x00007fb8faee257a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#6  0x00007fb8facfebe4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#7  0x00007fb8fdfc7136 in ?? () from /usr/lib/libQt5Quick.so.5
#8  0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#9  0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#10 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 9 (Thread 0x7fb80f7fd700 (LWP 5933)):
#0  0x00007fb8f9e2607f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fb8fad04e2b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQt5Core.so.5
#2  0x00007fb844baa37f in ThreadWeaver::Weaver::takeFirstAvailableJobOrSuspendOrWait(ThreadWeaver::Thread*, bool, bool, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#3  0x00007fb844baeb28 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#4  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#5  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#6  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#7  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#8  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#9  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#10 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#11 0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#12 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#13 0x00007fb844bac3c3 in ThreadWeaver::Thread::run() () from /usr/lib/libKF5ThreadWeaver.so.5
#14 0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#15 0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#16 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 8 (Thread 0x7fb8194b1700 (LWP 5934)):
#0  0x00007fb8f9e2607f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fb8fad04e2b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQt5Core.so.5
#2  0x00007fb844baa37f in ThreadWeaver::Weaver::takeFirstAvailableJobOrSuspendOrWait(ThreadWeaver::Thread*, bool, bool, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#3  0x00007fb844baeb28 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#4  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#5  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#6  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#7  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#8  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#9  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#10 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#11 0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#12 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#13 0x00007fb844bac3c3 in ThreadWeaver::Thread::run() () from /usr/lib/libKF5ThreadWeaver.so.5
#14 0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#15 0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#16 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 7 (Thread 0x7fb80fffe700 (LWP 5935)):
#0  0x00007fb8f9e2607f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fb8fad04e2b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQt5Core.so.5
#2  0x00007fb844baa37f in ThreadWeaver::Weaver::takeFirstAvailableJobOrSuspendOrWait(ThreadWeaver::Thread*, bool, bool, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#3  0x00007fb844baeb28 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#4  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#5  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#6  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#7  0x00007fb844bac3c3 in ThreadWeaver::Thread::run() () from /usr/lib/libKF5ThreadWeaver.so.5
#8  0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#9  0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#10 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 6 (Thread 0x7fb81b0fb700 (LWP 5936)):
#0  0x00007fb8f9e2607f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fb8fad04e2b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQt5Core.so.5
#2  0x00007fb844baa37f in ThreadWeaver::Weaver::takeFirstAvailableJobOrSuspendOrWait(ThreadWeaver::Thread*, bool, bool, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#3  0x00007fb844baeb28 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#4  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#5  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#6  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#7  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#8  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#9  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#10 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#11 0x00007fb844bac3c3 in ThreadWeaver::Thread::run() () from /usr/lib/libKF5ThreadWeaver.so.5
#12 0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#13 0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#14 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 5 (Thread 0x7fb822fab700 (LWP 5937)):
#0  0x00007fb8f9e2607f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fb8fad04e2b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQt5Core.so.5
#2  0x00007fb844baa37f in ThreadWeaver::Weaver::takeFirstAvailableJobOrSuspendOrWait(ThreadWeaver::Thread*, bool, bool, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#3  0x00007fb844baeb28 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#4  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#5  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#6  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#7  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#8  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#9  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#10 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#11 0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#12 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#13 0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#14 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#15 0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#16 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#17 0x00007fb844bac3c3 in ThreadWeaver::Thread::run() () from /usr/lib/libKF5ThreadWeaver.so.5
#18 0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#19 0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#20 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 4 (Thread 0x7fb8227aa700 (LWP 5938)):
#0  0x00007fb8f9e2607f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fb8fad04e2b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQt5Core.so.5
#2  0x00007fb844baa37f in ThreadWeaver::Weaver::takeFirstAvailableJobOrSuspendOrWait(ThreadWeaver::Thread*, bool, bool, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#3  0x00007fb844baeb28 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#4  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#5  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#6  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#7  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#8  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#9  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#10 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#11 0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#12 0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#13 0x00007fb844bac3c3 in ThreadWeaver::Thread::run() () from /usr/lib/libKF5ThreadWeaver.so.5
#14 0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#15 0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#16 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 3 (Thread 0x7fb821fa9700 (LWP 5939)):
#0  0x00007fb8f9e2607f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fb8fad04e2b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQt5Core.so.5
#2  0x00007fb844baa37f in ThreadWeaver::Weaver::takeFirstAvailableJobOrSuspendOrWait(ThreadWeaver::Thread*, bool, bool, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#3  0x00007fb844baeb28 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#4  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#5  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#6  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#7  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#8  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#9  0x00007fb844bac3c3 in ThreadWeaver::Thread::run() () from /usr/lib/libKF5ThreadWeaver.so.5
#10 0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#11 0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#12 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 2 (Thread 0x7fb8217a8700 (LWP 5940)):
#0  0x00007fb8f9e2607f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fb8fad04e2b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQt5Core.so.5
#2  0x00007fb844baa37f in ThreadWeaver::Weaver::takeFirstAvailableJobOrSuspendOrWait(ThreadWeaver::Thread*, bool, bool, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#3  0x00007fb844baeb28 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#4  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#5  0x00007fb844baeb82 in ?? () from /usr/lib/libKF5ThreadWeaver.so.5
#6  0x00007fb844ba9433 in ThreadWeaver::Weaver::applyForWork(ThreadWeaver::Thread*, bool) () from /usr/lib/libKF5ThreadWeaver.so.5
#7  0x00007fb844bac3c3 in ThreadWeaver::Thread::run() () from /usr/lib/libKF5ThreadWeaver.so.5
#8  0x00007fb8fad03b8e in ?? () from /usr/lib/libQt5Core.so.5
#9  0x00007fb8f9e204a4 in start_thread () from /usr/lib/libpthread.so.0
#10 0x00007fb8fa62113d in clone () from /usr/lib/libc.so.6

Thread 1 (Thread 0x7fb8fffe2800 (LWP 1862)):
[KCrash Handler]
#5  0x00007fb8fe4e83f0 in Plasma::Applet::actions() const () from /usr/lib/libKF5Plasma.so.5
#6  0x0000000000456289 in ShellCorona::addOutput(QSharedPointer<KScreen::Output> const&) ()
#7  0x000000000045640f in ShellCorona::outputEnabledChanged() ()
#8  0x00007fb8faf131a7 in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQt5Core.so.5
#9  0x00007fb8ff193717 in KScreen::Output::apply(QSharedPointer<KScreen::Output> const&) () from /usr/lib/libKF5Screen.so.6
#10 0x00007fb8ff17ff9e in KScreen::Config::apply(QSharedPointer<KScreen::Config> const&) () from /usr/lib/libKF5Screen.so.6
#11 0x00007fb8ff186219 in KScreen::ConfigMonitor::Private::updateConfigs(QSharedPointer<KScreen::Config> const&) () from /usr/lib/libKF5Screen.so.6
#12 0x00007fb8ff188509 in KScreen::ConfigMonitor::Private::edidReady(QDBusPendingCallWatcher*) () from /usr/lib/libKF5Screen.so.6
#13 0x00007fb8faf131a7 in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQt5Core.so.5
#14 0x00007fb90016a11f in QDBusPendingCallWatcher::finished(QDBusPendingCallWatcher*) () from /usr/lib/libQt5DBus.so.5
#15 0x00007fb90016b7f5 in ?? () from /usr/lib/libQt5DBus.so.5
#16 0x00007fb8faf141e1 in QObject::event(QEvent*) () from /usr/lib/libQt5Core.so.5
#17 0x00007fb8fb9e89ac in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQt5Widgets.so.5
#18 0x00007fb8fb9ede86 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQt5Widgets.so.5
#19 0x00007fb8faee4bab in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQt5Core.so.5
#20 0x00007fb8faee6fa6 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/libQt5Core.so.5
#21 0x00007fb8faf3b143 in ?? () from /usr/lib/libQt5Core.so.5
#22 0x00007fb8f7591dc7 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#23 0x00007fb8f7592020 in ?? () from /usr/lib/libglib-2.0.so.0
#24 0x00007fb8f75920cc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#25 0x00007fb8faf3b54f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#26 0x00007fb8faee257a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#27 0x00007fb8faeea53c in QCoreApplication::exec() () from /usr/lib/libQt5Core.so.5
#28 0x000000000043138a in main ()

I think I have closed and reopened again the lid something like 30 times before the session has been unlocked.
Comment 10 Nils 2016-02-03 13:25:51 UTC 
PS: While unlocking through this way, the panel disappears from my desktop environment, while it was configured for the user (which, like I said, has a password configured & required in order to login).
Comment 11 Martin Flöser 2016-02-09 15:33:57 UTC 
Git commit fae65f1cdd6446042b31ccd0eafd7a4c0b6623e3 by Martin Gräßlin.
Committed on 09/02/2016 at 14:41.
Pushed by graesslin into branch 'Plasma/5.5'.

[greeter] Dont quit when last window closes

Qt allows to have no screens. If all XRandR screens are disconnected
there are also no QScreens. This is from an X11 perspective wrong, but
we have to deal with it. No QScreens means that all views are destroyed
and no new ones are created. Thus all windows close and the greeter
exited successfully which in turn unlocked the screen.

This change ensures that the greeter doesn't exit when all windows close.

Funnily this was not a problem with the well known issue of Qt
crashing when all screens are disconnected. The lock screen handles
crashes gracefully and just restarts or more likely Qt also crashes
the application using KSld and thus taking down the complete session.
FIXED-IN: 5.5.5

M  +1    -0    greeter/main.cpp

http://commits.kde.org/kscreenlocker/fae65f1cdd6446042b31ccd0eafd7a4c0b6623e3
Comment 12 Martin Flöser 2016-02-09 15:38:36 UTC 
Git commit 5651785ad6663e2ef4d12a94b0b5f1cb7d40a9a1 by Martin Gräßlin.
Committed on 09/02/2016 at 15:37.
Pushed by graesslin into branch 'Plasma/5.0'.

[greeter] Dont quit when last window closes

Qt allows to have no screens. If all XRandR screens are disconnected
there are also no QScreens. This is from an X11 perspective wrong, but
we have to deal with it. No QScreens means that all views are destroyed
and no new ones are created. Thus all windows close and the greeter
exited successfully which in turn unlocked the screen.

This change ensures that the greeter doesn't exit when all windows close.

Funnily this was not a problem with the well known issue of Qt
crashing when all screens are disconnected. The lock screen handles
crashes gracefully and just restarts or more likely Qt also crashes
the application using KSld and thus taking down the complete session.

M  +1    -0    ksmserver/screenlocker/greeter/main.cpp

http://commits.kde.org/plasma-workspace/5651785ad6663e2ef4d12a94b0b5f1cb7d40a9a1
Comment 13 Martin Flöser 2016-02-09 15:39:39 UTC 
Git commit 1fe565e5dae31e57d81556b07e7459be14c5d834 by Martin Gräßlin.
Committed on 09/02/2016 at 15:39.
Pushed by graesslin into branch 'Plasma/5.1'.

[greeter] Dont quit when last window closes

Qt allows to have no screens. If all XRandR screens are disconnected
there are also no QScreens. This is from an X11 perspective wrong, but
we have to deal with it. No QScreens means that all views are destroyed
and no new ones are created. Thus all windows close and the greeter
exited successfully which in turn unlocked the screen.

This change ensures that the greeter doesn't exit when all windows close.

Funnily this was not a problem with the well known issue of Qt
crashing when all screens are disconnected. The lock screen handles
crashes gracefully and just restarts or more likely Qt also crashes
the application using KSld and thus taking down the complete session.

M  +1    -0    ksmserver/screenlocker/greeter/main.cpp

http://commits.kde.org/plasma-workspace/1fe565e5dae31e57d81556b07e7459be14c5d834
Comment 14 Martin Flöser 2016-02-09 15:40:22 UTC 
Git commit e1036973552a8964dffcbca0743eb1accc14bc56 by Martin Gräßlin.
Committed on 09/02/2016 at 15:40.
Pushed by graesslin into branch 'Plasma/5.2'.

[greeter] Dont quit when last window closes

Qt allows to have no screens. If all XRandR screens are disconnected
there are also no QScreens. This is from an X11 perspective wrong, but
we have to deal with it. No QScreens means that all views are destroyed
and no new ones are created. Thus all windows close and the greeter
exited successfully which in turn unlocked the screen.

This change ensures that the greeter doesn't exit when all windows close.

Funnily this was not a problem with the well known issue of Qt
crashing when all screens are disconnected. The lock screen handles
crashes gracefully and just restarts or more likely Qt also crashes
the application using KSld and thus taking down the complete session.

M  +1    -0    ksmserver/screenlocker/greeter/main.cpp

http://commits.kde.org/plasma-workspace/e1036973552a8964dffcbca0743eb1accc14bc56
Comment 15 Martin Flöser 2016-02-09 15:41:02 UTC 
Git commit de6e19fd8c30166bdbc1333dcd5ef2278f570fa2 by Martin Gräßlin.
Committed on 09/02/2016 at 15:40.
Pushed by graesslin into branch 'Plasma/5.3'.

[greeter] Dont quit when last window closes

Qt allows to have no screens. If all XRandR screens are disconnected
there are also no QScreens. This is from an X11 perspective wrong, but
we have to deal with it. No QScreens means that all views are destroyed
and no new ones are created. Thus all windows close and the greeter
exited successfully which in turn unlocked the screen.

This change ensures that the greeter doesn't exit when all windows close.

Funnily this was not a problem with the well known issue of Qt
crashing when all screens are disconnected. The lock screen handles
crashes gracefully and just restarts or more likely Qt also crashes
the application using KSld and thus taking down the complete session.

M  +1    -0    ksmserver/screenlocker/greeter/main.cpp

http://commits.kde.org/plasma-workspace/de6e19fd8c30166bdbc1333dcd5ef2278f570fa2
Comment 16 Martin Flöser 2016-02-09 15:41:49 UTC 
Git commit 23a9ed7ba9995570227dbcd69c23f009de7dde49 by Martin Gräßlin.
Committed on 09/02/2016 at 15:41.
Pushed by graesslin into branch 'Plasma/5.4'.

[greeter] Dont quit when last window closes

Qt allows to have no screens. If all XRandR screens are disconnected
there are also no QScreens. This is from an X11 perspective wrong, but
we have to deal with it. No QScreens means that all views are destroyed
and no new ones are created. Thus all windows close and the greeter
exited successfully which in turn unlocked the screen.

This change ensures that the greeter doesn't exit when all windows close.

Funnily this was not a problem with the well known issue of Qt
crashing when all screens are disconnected. The lock screen handles
crashes gracefully and just restarts or more likely Qt also crashes
the application using KSld and thus taking down the complete session.

M  +1    -0    ksmserver/screenlocker/greeter/main.cpp

http://commits.kde.org/plasma-workspace/23a9ed7ba9995570227dbcd69c23f009de7dde49
Comment 17 Nils 2016-02-09 16:12:40 UTC 
Wow, thank you very much! I was afraid to see this bug never solved as it seem that no one was facing it/able to reproduce it. 
It is the second bug I have reported fixed this week, great job to you. :)