[FFmpeg-trac] #3120(undetermined:new): Crash when converting internal SSA to SRT

[FFmpeg]

#3120: Crash when converting internal SSA to SRT
-------------------------------------+-------------------------------------
             Reporter:  eelco        |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:

 ffmpeg can crash when extracting an SSA subtitle to an SRT file.

 How to reproduce:
 {{{
 % ffmpeg -i ssa-2-srt-fails.mkv out.srt
 ffmpeg version N-57932-g89a3be8 Copyright (c) 2000-2013 the FFmpeg
 developers
   built on Nov  5 2013 16:30:18 with Apple LLVM version 5.0
 (clang-500.2.78) (based on LLVM 3.3svn)
   configuration: --prefix=/Users/eelco/Projects/Beamer/FFmpeg/build
 --disable-shared
   libavutil      52. 52.100 / 52. 52.100
   libavcodec     55. 41.100 / 55. 41.100
   libavformat    55. 21.100 / 55. 21.100
   libavdevice    55.  5.100 / 55.  5.100
   libavfilter     3. 90.102 /  3. 90.102
   libswscale      2.  5.101 /  2.  5.101
   libswresample   0. 17.104 /  0. 17.104
 [matroska,webm @ 0x7fd09b817a00] Unknown entry 0x437E
     Last message repeated 4 times
 Input #0, matroska,webm, from 'ssa-2-srt-fails.mkv':
   Metadata:
     creation_time   : 2013-04-07 06:15:26
   Duration: 00:24:06.45, start: 0.000000, bitrate: 3041 kb/s
     Chapter #0.0: start 0.033000, end 123.498375
     Metadata:
       title           : Intro
     Chapter #0.1: start 123.498375, end 214.964750
     Metadata:
       title           : OP
     Chapter #0.2: start 214.964750, end 752.793708
     Metadata:
       title           : Part A
     Chapter #0.3: start 752.793708, end 1431.596833
     Metadata:
       title           : Part B
     Chapter #0.4: start 1431.596833, end 1446.445000
     Metadata:
       title           : Preview
     Stream #0:0(eng): Video: h264 (High 10), yuv420p10le, 1280x720, SAR
 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
     Stream #0:1(jpn): Audio: aac, 48000 Hz, stereo, fltp (default)
     Metadata:
       title           : Commie
     Stream #0:2(eng): Subtitle: ssa (default)
 Codec 0x18000 is not in the full list.
     Stream #0:3: Attachment: unknown_codec
     Metadata:
       filename        : Comfortaa-Regular.ttf
       mimetype        : application/x-truetype-font
 Codec 0x18000 is not in the full list.
     Stream #0:4: Attachment: unknown_codec
     Metadata:
       filename        : LT.ttf
       mimetype        : application/x-truetype-font
 Codec 0x18000 is not in the full list.
     Stream #0:5: Attachment: unknown_codec
     Metadata:
       filename        : LTFinnegan_MediumItalic.ttf
       mimetype        : application/x-truetype-font
 Codec 0x18000 is not in the full list.
     Stream #0:6: Attachment: unknown_codec
     Metadata:
       filename        : Cavalier.ttf
       mimetype        : application/x-truetype-font
 Codec 0x18000 is not in the full list.
     Stream #0:7: Attachment: unknown_codec
     Metadata:
       filename        : Comfortaa-Bold.ttf
       mimetype        : application/x-truetype-font
 Codec 0x18000 is not in the full list.
     Stream #0:8: Attachment: unknown_codec
     Metadata:
       filename        : DSFetteKanzlei.ttf
       mimetype        : application/x-truetype-font
 Codec 0x18000 is not in the full list.
     Stream #0:9: Attachment: unknown_codec
     Metadata:
       filename        : KaiserzeitGotisch.ttf
       mimetype        : application/x-truetype-font
 Codec 0x18000 is not in the full list.
     Stream #0:10: Attachment: unknown_codec
     Metadata:
       filename        : Mothproof_Script.ttf
       mimetype        : application/x-truetype-font
 Output #0, srt, to 'out.srt':
   Metadata:
     encoder         : Lavf55.21.100
     Chapter #0.0: start 0.033000, end 123.498375
     Metadata:
       title           : Intro
     Chapter #0.1: start 123.498375, end 214.964750
     Metadata:
       title           : OP
     Chapter #0.2: start 214.964750, end 752.793708
     Metadata:
       title           : Part A
     Chapter #0.3: start 752.793708, end 1431.596833
     Metadata:
       title           : Part B
     Chapter #0.4: start 1431.596833, end 1446.445000
     Metadata:
       title           : Preview
     Stream #0:0(eng): Subtitle: subrip (default)
 Stream mapping:
   Stream #0:2 -> #0:0 (ssa -> subrip)
 Press [q] to stop, [?] for help
 ffmpeg(11976,0x7fff77cc8310) malloc: *** error for object 0x7fd09b8a6e08:
 incorrect checksum for freed object - object was probably modified after
 being freed.
 *** set a breakpoint in malloc_error_break to debug
 fish: Job 1, 'ffmpeg -i ssa-2-srt-fails.mkv out.srt' terminated by signal
 SIGABRT (Abort)
 }}}

 Note that the crash does not seem to occur at the same point in the file
 between different runs.

 File will be uploaded to the FTP.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/3120>
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