[gstreamer-bugs] [Bug 386218] New: [asfdemux] Division by zero when seeking live streams

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gst-plugins-ugly | Ver: HEAD CVS

           Summary: [asfdemux] Division by zero when seeking live streams
           Product: GStreamer
           Version: HEAD CVS
          Platform: Other
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-ugly
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: riccardo.brigo at sssup.it
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


Symptom: trying to perform a seek over an asf file reporting play_time == 0
(live stream) causes the application to crash with a "floating point exception"
Expected result: gst_element_seek should report failure to seek

Details:

In file gst-plugins-ugly-0.10.5/gst/asfdemux/gstasfdemux.c:274

 seek_packet = demux->num_packets * seek_time / demux->play_time;

but nobody checks, before of this statement, that demux->play_time is valid/not
null, so the application crashes with a "floating point exception".

In my case the problem arises when trying to seek a file originating from the
capture of a live stream, for which the file correctly reports (line numbers
are from version 0.10.4 of plugins-ugly, but relevant code is unchanged in
0.10.5):

gstasfdemux.c:1698:gst_asf_demux_process_ext_stream_props: start_time          
  = 0:00:00.000000000
gstasfdemux.c:1700:gst_asf_demux_process_ext_stream_props: end_time            
  = 0:00:00.000000000
gstasfdemux.c:1701:gst_asf_demux_process_ext_stream_props: flags               
  = 00000000
gstasfdemux.c:1703:gst_asf_demux_process_ext_stream_props: average time per
frame = 0:00:00.000000000
gstasfdemux.c:1704:gst_asf_demux_process_ext_stream_props: stream number       
  = 1
gstasfdemux.c:1707:gst_asf_demux_process_ext_stream_props: stream language ID
idx = 1 (it)
gstasfdemux.c:1708:gst_asf_demux_process_ext_stream_props: stream name count   
  = 0
gstasfdemux.c:1723:gst_asf_demux_process_ext_stream_props: payload ext sys
count = 0
gstasfdemux.c:1736:gst_asf_demux_process_ext_stream_props: bytes read: 64/64
0

The seeking function should check the "seekable" flag (least significant bit of
demux->ext_stream_props.flags) or at least guard against demux->play_time == 0
(which IMHO is anyway a good idea, in order to protect the application from
malformed headers), and return a "normal" failure.

Riccardo Brigo


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