Comment 5 for bug 38530

I can duplicate this bug. I don't have wireless, but it my dapper updated from yesterday I can duplicate. the package in question is:
kde-systemsettings version 0.0svn20060413-0ubuntu1

Steps to reproduce the bug:
1. make /etc/network/interfaces same as above (only define loopback device)
2. restart networking (/etc/init.d/networking restart)
2. sudo ifconfig eth0 0.0.0.0 (my card still had dhcp address after restarting networking and removing eth0 reference in /etc/network/interfaces)
3. go to system-settings, network, click administrator mode and enter your password. you should receive a crash when you click on configure interface.

So the criteria are:
1 /etc/network/interfaces has no reference to eth0
2 eth0 is up but has no ip address

putting the reference back into /etc/network/interfaces to eth0 stops the problem. (even with an ip of 0.0.0.0) and removing the reference, but having a non-zero ip address also doesnt cause the crash.

I have tested this in most combinations I can think of.

here is the backtrace

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Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
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[Thread debugging using libthread_db enabled]
[New Thread -1232143712 (LWP 16416)]
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[KCrash handler]
#6 0xb7dec476 in inet_pton () from /lib/tls/i686/cmov/libc.so.6
#7 0xb663ca35 in KAddressValidator::calculateBroadcast ()
   from /usr/lib/kde3/kcm_knetworkconfmodule.so
#8 0xb6657da2 in KNetworkConf::configureDeviceSlot ()
   from /usr/lib/kde3/kcm_knetworkconfmodule.so
#9 0xb663a2cd in KNetworkConfDlg::qt_invoke ()
   from /usr/lib/kde3/kcm_knetworkconfmodule.so
#10 0xb6661231 in KNetworkConf::qt_invoke ()
   from /usr/lib/kde3/kcm_knetworkconfmodule.so
#11 0xb6e92e29 in QObject::activate_signal () from /usr/lib/libqt-mt.so.3
#12 0xb6e938c4 in QObject::activate_signal () from /usr/lib/libqt-mt.so.3
#13 0xb722e89f in QButton::clicked () from /usr/lib/libqt-mt.so.3
#14 0xb6f2e46a in QButton::mouseReleaseEvent () from /usr/lib/libqt-mt.so.3
#15 0xb6ecd5fd in QWidget::event () from /usr/lib/libqt-mt.so.3
#16 0xb6e28dc6 in QApplication::internalNotify () from /usr/lib/libqt-mt.so.3
#17 0xb6e29350 in QApplication::notify () from /usr/lib/libqt-mt.so.3
#18 0xb75d0d7d in KApplication::notify () from /usr/lib/libkdecore.so.4
#19 0xb6dba15d in QApplication::sendSpontaneousEvent ()
   from /usr/lib/libqt-mt.so.3
#20 0xb6db580b in QETWidget::translateMouseEvent ()
   from /usr/lib/libqt-mt.so.3
#21 0xb6db3cf1 in QApplication::x11ProcessEvent () from /usr/lib/libqt-mt.so.3
#22 0xb6dcd473 in QEventLoop::processEvents () from /usr/lib/libqt-mt.so.3
#23 0xb6e418b7 in QEventLoop::enterLoop () from /usr/lib/libqt-mt.so.3
#24 0xb6e417da in QEventLoop::exec () from /usr/lib/libqt-mt.so.3
#25 0xb6e278d5 in QApplication::exec () from /usr/lib/libqt-mt.so.3
#26 0xb7f4e426 in kdemain () from /usr/lib/libkdeinit_kcmshell.so
#27 0xb7d29ea2 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#28 0x080483b5 in ?? ()