python: double free or corruption (out)

[Angel Guzman Maeso]

Testing the code attached and extracted from

http://bazaar.launchpad.net/~jderose/+junk/gst-examples/view/head:/webcam-1.0

https://wiki.ubuntu.com/Novacut/GStreamer1.0

*** glibc detected *** python: double free or corruption (out): 0xb3467ed0 ***
======= Backtrace: =========
/lib/i386-linux-gnu/libc.so.6(+0x73e42)[0xb73a5e42]
/usr/lib/i386-linux-gnu/libX11.so.6(+0x368ff)[0xb624f8ff]
/usr/lib/i386-linux-gnu/libX11.so.6(_XEventsQueued+0x68)[0xb62503e8]
/usr/lib/i386-linux-gnu/libX11.so.6(XPending+0x68)[0xb6241188]
/usr/lib/i386-linux-gnu/libgdk-3.so.0(+0x4ad64)[0xb63a4d64]
/usr/lib/i386-linux-gnu/libgdk-3.so.0(+0x4add3)[0xb63a4dd3]
/lib/i386-linux-gnu/libglib-2.0.so.0(g_main_context_check+0x19f)[0xb6d6583f]
/lib/i386-linux-gnu/libglib-2.0.so.0(+0x46d02)[0xb6d65d02]
/lib/i386-linux-gnu/libglib-2.0.so.0(g_main_loop_run+0x7b)[0xb6d6624b]
/usr/lib/i386-linux-gnu/libgtk-3.so.0(gtk_main+0x9d)[0xb6584d5d]
/usr/lib/i386-linux-gnu/libffi.so.6(ffi_call_SYSV+0x1a)[0xb6bb535a]
/usr/lib/i386-linux-gnu/libffi.so.6(ffi_call+0x6f)[0xb6bb508f]
/usr/lib/libgirepository-1.0.so.1(g_callable_info_invoke+0x38d)[0xb6e735cd]
/usr/lib/libgirepository-1.0.so.1(g_function_info_invoke+0xa4)[0xb6e74ba4]
/usr/lib/python2.7/dist-packages/gi/_gi.so(+0x1155a)[0xb6ede55a]
/usr/lib/python2.7/dist-packages/gi/_gi.so(+0x12260)[0xb6edf260]
python(PyEval_EvalFrameEx+0x3ead)[0x808c7bd]
python(PyEval_EvalCodeEx+0x150)[0x81a7d70]
python(PyEval_EvalFrameEx+0x6cc)[0x8088fdc]
python(PyEval_EvalFrameEx+0x7bc)[0x80890cc]
python(PyEval_EvalCodeEx+0x150)[0x81a7d70]
python(PyRun_SimpleFileExFlags+0x2c1)[0x8151e21]
python(Py_Main+0x559)[0x815a4d9]
python(main+0x1b)[0x805e78b]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb734b4d3]
python[0x805e7b1]
======= Memory map: ========
08048000-0829f000 r-xp 00000000 08:07 3015493 /usr/bin/python2.7
0829f000-082a0000 r--p 00256000 08:07 3015493 /usr/bin/python2.7
082a0000-082f5000 rw-p 00257000 08:07 3015493 /usr/bin/python2.7
082f5000-08301000 rw-p 00000000 00:00 0
09ec1000-0a284000 rw-p 00000000 00:00 0 [heap]
b2a00000-b2c80000 rw-s 00780000 00:05 8935 /dev/video0
b2c80000-b2f00000 rw-s 00500000 00:05 8935 /dev/video0
b2f00000-b3180000 rw-s 00280000 00:05 8935 /dev/video0
b3180000-b3400000 rw-s 00000000 00:05 8935 /dev/video0
b3400000-b346d000 rw-p 00000000 00:00 0
b346d000-b3500000 ---p 00000000 00:00 0
b353b000-b353c000 ---p 00000000 00:00 0
b353c000-b3d3c000 rw-p 00000000 00:00 0 [stack:6249]
b3d3c000-b3d80000 r-xp 00000000 08:07 3039227 /usr/lib/i386-linux-gnu/libjpeg.so.8.0.2
b3d80000-b3d81000 r--p 00043000 08:07 3039227 /usr/lib/i386-linux-gnu/libjpeg.so.8.0.2
b3d81000-b3d82000 rw-p 00044000 08:07 3039227 /usr/lib/i386-linux-gnu/libjpeg.so.8.0.2
b3d82000-b3d92000 rw-p 00000000 00:00 0
b3d92000-b3db6000 r-xp 00000000 08:07 3019345 /usr/lib/i386-linux-gnu/libv4lconvert.so.0
b3db6000-b3db7000 r--p 00024000 08:07 3019345 /usr/lib/i386-linux-gnu/libv4lconvert.so.0
b3db7000-b3db8000 rw-p 00025000 08:07 3019345 /usr/lib/i386-linux-gnu/libv4lconvert.so.0
b3db8000-b3e0a000 rw-p 00000000 00:00 0
b3e35000-b3e36000 ---p 00000000 00:00 0
b3e36000-b4636000 rw-p 00000000 00:00 0 [stack:6248]
b4636000-b46c1000 r-xp 00000000 08:07 3045207 /usr/lib/i386-linux-gnu/liborc-0.4.so.0.16.0
b46c1000-b46c2000 r--p 0008a000 08:07 3045207 /usr/lib/i386-linux-gnu/liborc-0.4.so.0.16.0
b46c2000-b46c6000 rw-p 0008b000 08:07 3045207 /usr/lib/i386-linux-gnu/liborc-0.4.so.0.16.0
b46c6000-b46fb000 r-xp 00000000 08:07 3014814 /usr/lib/i386-linux-gnu/libgstvideo-1.0.so.0.0.0
b46fb000-b46fc000 ---p 00035000 08:07 3014814 /usr/lib/i386-linux-gnu/libgstvideo-1.0.so.0.0.0
b46fc000-b46fd000 r--p 00035000 08:07 3014814 /usr/lib/i386-linux-gnu/libgstvideo-1.0.so.0.0.0
b46fd000-b4700000 rw-p 00036000 08:07 3014814 /usr/lib/i386-linux-gnu/libgstvideo-1.0.so.0.0.0
b4700000-b4721000 rw-p 00000000 00:00 0
b4721000-b4800000 ---p 00000000 00:00 0
b481a000-b483e000 r-xp 00000000 08:07 331428 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstvideo4linux2.so
b483e000-b483f000 r--p 00023000 08:07 331428 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstvideo4linux2.so
b483f000-b4840000 rw-p 00024000 08:07 331428 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstvideo4linux2.so
b4840000-b4897000 r-xp 00000000 08:07 3015457 /usr/lib/i386-linux-gnu/libgstbase-1.0.so.0.0.0
b4897000-b4898000 r--p 00056000 08:07 3015457 /usr/lib/i386-linux-gnu/libgstbase-1.0.so.0.0.0
b4898000-b4899000 rw-p 00057000 08:07 3015457 /usr/lib/i386-linux-gnu/libgstbase-1.0.so.0.0.0
b4899000-b48e3000 r-xp 00000000 08:07 295096 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstcoreelements.so
b48e3000-b48e4000 r--p 00049000 08:07 295096 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstcoreelements.so
b48e4000-b48e5000 rw-p 0004a000 08:07 295096 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstcoreelements.so
b48e5000-b48e6000 ---p 00000000 00:00 0
b48e6000-b50e6000 rw-p 00000000 00:00 0 [stack:6239]
b50e6000-b51d0000 r-xp 00000000 08:07 3015501 /usr/lib/i386-linux-gnu/libgstreamer-1.0.so.0.0.0
b51d0000-b51d3000 r--p 000ea000 08:07 3015501 /usr/lib/i386-linux-gnu/libgstreamer-1.0.so.0.0.0
b51d3000-b51d4000 rw-p 000ed000 08:07 3015501 /usr/lib/i386-linux-gnu/libgstreamer-1.0.so.0.0.0
b51d4000-b51d5000 rw-p 00000000 00:00 0
b51db000-b51e3000 r-xp 00000000 08:07 3030507 /usr/lib/i386-linux-gnu/libv4l2.so.0
b51e3000-b51e4000 r--p 00007000 08:07 3030507 /usr/lib/i386-linux-gnu/libv4l2.so.0
b51e4000-b51e8000 rw-p 00008000 08:07 3030507 /usr/lib/i386-linux-gnu/libv4l2.so.0
b51e8000-b51ec000 r-xp 00000000 08:07 3037220 /usr/lib/i386-linux-gnu/libXv.so.1.0.0
b51ec000-b51ed000 r--p 00003000 08:07 3037220 /usr/lib/i386-linux-gnu/libXv.so.1.0.0
b51ed000-b51ee000 rw-p 00004000 08:07 3037220 /usr/lib/i386-linux-gnu/libXv.so.1.0.0
b51ee000-b51fe000 r-xp 00000000 08:07 298598 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstxvimagesink.so
b51fe000-b51ff000 r--p 0000f000 08:07 298598 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstxvimagesink.so
b51ff000-b5200000 rw-p 00010000 08:07 298598 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstxvimagesink.so
b5200000-b5221000 rw-p 00000000 00:00 0
b5221000-b5300000 ---p 00000000 00:00 0
b5305000-b530d000 r-xp 00000000 08:07 331384 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstautodetect.so
b530d000-b530e000 r--p 00007000 08:07 331384 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstautodetect.so
b530e000-b530f000 rw-p 00008000 08:07 331384 /usr/lib/i386-linux-gnu/gstreamer-1.0/libgstautodetect.so
b530f000-b5318000 r--p 00000000 08:07 1313986 /usr/share/locale/es/LC_MESSAGES/gstreamer-1.0.mo
b5318000-b5322000 r--p 00000000 08:07 3029860 /usr/lib/girepository-1.0/GstBase-1.0.typelibAbortado (`core' generado)

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: python2.7 2.7.3-0ubuntu3
ProcVersionSignature: Ubuntu 3.5.0-1.1-generic 3.5.0-rc3
Uname: Linux 3.5.0-1-generic i686
ApportVersion: 2.2.5-0ubuntu1
Architecture: i386
Date: Tue Jun 26 14:21:37 2012
InstallationMedia:

ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=es_ES.UTF-8
 SHELL=/bin/bash
SourcePackage: python2.7
UpgradeStatus: Upgraded to quantal on 2012-06-05 (21 days ago)

[Angel Guzman Maeso (shakaran)]

On followings calls to the program, it generates core dumps or this message:

prepare-window-handle
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
python: ../../src/xcb_io.c:273: poll_for_event: La declaración `!xcb_xlib_threads_sequence_lost' no se cumple.

It is difficult to reproduce, but there are some memory corruption, probably with some module that try to release memory twice

[Angel Guzman Maeso (shakaran)]

I filled a upstream bug more complete on gstreamer https://bugzilla.gnome.org/show_bug.cgi?id=678897

The problem seems is with gstreamer that raises the segfault on python.

[Jason Gerard DeRose (jderose)]

Hi everyone, thanks for filing this bug and for testing my tutorial examples!

I was out-of-touch with some Gtk changes... you can no longer get the XID inside the prepare-xwindow-id/prepare-window-handle callback. Instead, you need to get the XID after you call window.show_all(), before you call Gtk.main().

I updated my examples with this fix:

http://bazaar.launchpad.net/~jderose/+junk/gst-examples/view/head:/webcam-1.0

http://bazaar.launchpad.net/~jderose/+junk/gst-examples/view/head:/webcam-0.10

And I also made a note about this in my porting guide:

https://wiki.ubuntu.com/Novacut/GStreamer1.0#prepare-xwindow-id

Big thanks to Tim-Philipp Müller (__tim in the #gstreamer IRC channel) for pointing this out. Sorry to lead people astray!