[mythtv-commits] Re: Ticket #801: Mythbackend crash while generating thumbnails + bt, log

[MythTV]

#801: Mythbackend crash while generating thumbnails + bt, log
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 Reporter:  jr at jrh.net  |        Owner:  danielk 
     Type:  defect      |       Status:  reopened
 Priority:  minor       |    Milestone:  unknown 
Component:  mythtv      |      Version:  head    
 Severity:  medium      |   Resolution:          
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Comment (by jwestfall at surrealistic.net):

 I got this same issue today with a firewire recorded program and I think I
 see whats going on.

 av_find_stream_info will segfault if there is a stream change within the
 mpegts packets its using to find the stream info.  When a stream change
 happens the following trace happens


 {{{
 ==15109==    at 0x401B009: free (vg_replace_malloc.c:235)
 ==15109==    by 0x4927C87: av_free (mem.c:128)
 ==15109==    by 0x48BDF1E: flush_packet_queue (utils.c:1161)
 ==15109==    by 0x48BDFA4: av_read_frame_flush (utils.c:1195)
 ==15109==    by 0x48AAC3D: pmt_cb (mpegts.c:642)
 ==15109==    by 0x48AA1A4: write_section_data (mpegts.c:263)
 ==15109==    by 0x48AC488: handle_packet (mpegts.c:1523)
 ==15109==    by 0x48AC71C: handle_packets (mpegts.c:1604)
 ==15109==    by 0x48AD31F: mpegts_read_packet (mpegts.c:1892)
 ==15109==    by 0x48BCCAD: av_read_packet (utils.c:702)
 ==15109==    by 0x48BDA41: av_read_frame_internal (utils.c:1021)
 ==15109==    by 0x48C04AC: av_find_stream_info (utils.c:2066)

 }}}

 flush_packet_queue() frees all AVPackets on ic->packet_buffer, but
 av_find_stream_info() has its own pointer (*ppktl) that points to the last
 AVPacket on ci->packet_buffer.  The segfault is triggered next time
 av_find_stream_info() tries to append a packet to ic->packet_buffer using
 *ppktl.

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Ticket URL: <http://cvs.mythtv.org/trac/ticket/801>
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