Discussion:
Bug#891233: Bug #891233: kamoso: segmentation fault in kamoso in Debian 9 stable. Buster not affected
Bernhard Übelacker
6 years ago
Permalink
Dear Maintainer, hello Laura Arjona Reina,
I just tried to have a look at this crash.

Unfortunately given information point to no exact location.

In that case the line from dmesg would already be helpful:
[ 609.690904] kamoso[28487]: segfault at 0 ip 000055bc679e7fd5 sp 00007ffc474fd950 error 4 in kamoso[55bc679d3000+2b000]

A good information would be just to run it that way:
gdb -q -ex run -ex bt -ex detach -ex quit --args kamoso

Another way would be to install a core dump collector like systemd-coredump
and execute something like this:
coredumpctl list
coredumpctl gdb <PID>

Even better when debug symbols are installed like described in [1].


Nevertheless I could reproduce a crash in a minimal stretch amd64 qemu VM,
with a forwarded usb webcam.

(gdb) bt
#0 0x000055bc679e7fd5 in WebcamControl::play (this=***@entry=0x7ffc474fdc80, device=0x55bc68b82220) at ./src/video/webcamcontrol.cpp:135
#1 0x000055bc679e8bfd in WebcamControl::WebcamControl (this=0x7ffc474fdc80) at ./src/video/webcamcontrol.cpp:86
#2 0x000055bc679e071f in main (argc=<optimized out>, argv=0x7ffc474fdde8) at ./src/main.cpp:43

(gdb) print cameraSource
$1 = {m_class = 0x0}

134 auto cameraSource = QGst::ElementFactory::make("wrappercamerabinsrc", "video_balance");
135 cameraSource->setProperty("video-source-filter", bin);


That "wrappercamerabinsrc" points to a missing package gstreamer1.0-plugins-bad.
Maybe you can confirm that installing that package avoids the crash,
if you still run a stretch installation that shows it.

This crash got fixed upstream in [2].

Kind regards,
Bernhard

[1] https://wiki.debian.org/HowToGetABacktrace
[2] https://cgit.kde.org/kamoso.git/commit/?id=1ff5f14fedd42bfa61ae181e0c598ec991ba4407
Laura Arjona Reina
6 years ago
Permalink
Hello Bernhard, maintainers
Thanks for your help.
I'm attaching the result of the gdb command, and the result of the
coredumpctl command.

As you suggested, I have installed gstreamer1.0-plugins-bad, and after
that, I can confirm that kamoso runs well.

Note that together with gstreamer1.0-plugins-bad all these packages were
installed:
freepats gir1.2-gstreamer-1.0 gstreamer1.0-doc
gstreamer1.0-plugins-bad gstreamer1.0-plugins-bad-dbg
gstreamer1.0-plugins-bad-doc gstreamer1.0-plugins-base-doc libde265-0
libglib2.0-dev libglib2.0-doc libgstreamer1.0-dev libmjpegutils-2.1-0
libmms0 libmodplug1 libmpeg2encpp-2.1-0 libmplex2-2.1-0 libofa0
libpcre3-dev libpcre32-3 libpcrecpp0v5 libsbc1 libvo-aacenc0
libvo-amrwbenc0 libwildmidi-config libwildmidi2 libzbar0 zlib1g-dev

Hope that helps.
Kind regards,
--
Laura Arjona Reina
https://wiki.debian.org/LauraArjona
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