[CRASH] SegFault when generating previews for certain HD-PVR recordings

[doug@…]

My HD-PVR occasionally corrupts the beginning of its recordings. The recordings are watchable (if I fast forward the beginning) however, the mythbackend preview generator process will segfault when generating previews for these recordings (e.g. from MythWeb). I'm currently running trunk 23865 and attached are two sample back traces.

Thanks! Doug

# mythbackend --version Please include all output in bug reports. MythTV Version : 23865M MythTV Branch : trunk Network Protocol : 56 Library API : 0.23.20100326-1 QT Version : 4.5.2 Options compiled in:

linux debug using_oss using_alsa using_pulse using_pulseoutput using_backend using_directfb using_dvb using_firewire using_frontend using_hdhomerun using_hdpvr using_iptv using_ivtv using_joystick_menu using_lirc using_mheg using_opengl_video using_opengl_vsync using_qtdbus using_qtwebkit using_v4l using_x11 using_xrandr using_xv using_xvmc using_xvmc_vld using_xvmcw using_bindings_perl using_bindings_python using_opengl using_vdpau using_ffmpeg_threads using_libavc_5_3 using_live using_mheg

[jpoet]

VideoBuffers::CreateBuffers: check if av_malloc returns NULL

[jpoet]

Can you please try the attached CreateBuffers_check_NULL.patch and see if it helps?

[Doug Haber <doug@…>]

Awesome - thanks for the quick response - I'll check it out when I wake up tomorrow.

-Doug

[jpoet]

Actually, that patch probably will not help. Should not hurt, but unlikely to fix the problem.

Please try add_previewgenerator_logging.patch and attach a log after the crash happens.

[jpoet]

Add playback,extra logging to the preview generator

[Doug Haber <doug@…>]

jpoet - As you suspected, the first patch did not fix the segfault. Attached is the log.

[Doug Haber <doug@…>]

FWIW I get a SegFault and see the error on the same line for mythcommflag as well

[dougt@…]

stacktrace

[Doug Haber <doug@…>]

For what it's worth I still see this in trunk 25777 with mythpreviewgen.

[beirdo]

Not sure if that crash spew (from the console where I ran mythbackend) is deemed helpful or not. It may be pointing at an entirely different crash in mythpreviewgen.

[anonymous]

sad... i was hoping that the recent ffpeg merge would have helped. it didn't.

[beirdo]

See also #9063

[anonymous]

jpoet, can/will this be fixed for 0.24?

[beirdo]

See also #9596 (which was a DVB-T H.264 recording)

[beirdo]

A lot of things have changed in the code over the past year, is this still reproducable?

[Doug Haber <doug@…>]

This is way out of date for me. It's probably more relevant to just open a new ticket if it happens again.

Thanks!
Doug

[beirdo]

Closing at user request.