[FFmpeg-trac] #6873(avformat:open): Crash with muxing a lot of streams in Matroska

[FFmpeg]

#6873: Crash with muxing a lot of streams in Matroska
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             Reporter:  mkver        |                    Owner:
                 Type:  defect       |                   Status:  open
             Priority:  important    |                Component:  avformat
              Version:  git-master   |               Resolution:
             Keywords:  mkv crash    |               Blocked By:
  SIGSEGV regression                 |  Reproduced by developer:  1
             Blocking:               |
Analyzed by developer:  0            |
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Comment (by jamrial):

 Replying to [comment:6 cehoyos]:
 > For the 128 sample, this is a regression since
 7be0f48a32155ef9f471ffc5a1b41d662ea337f1
 That commit added a stream limit, but didn't enforce it anywhere...

 Of course things are crashing with more than 126 streams. Code introduced
 in that commit is trying to write timestamps beyond the
 last_track_timestamp buffer, overwriting unrelated fields in the
 MatroskaMuxContext struct in the process, which currently means the stream
 duration pointers.

 With more than 128 streams you would probably get a crash in lines
 2182/2184 instead.

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Ticket URL: <https://trac.ffmpeg.org/ticket/6873#comment:7>
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