[FFmpeg-trac] #764(avcodec:new): Increasing robustness of runlength decoding for scantable access in mpeg12.c

[FFmpeg]

#764: Increasing robustness of runlength decoding for scantable access in
mpeg12.c
-------------------------------------+-------------------------------------
             Reporter:  erik         |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  avcodec      |                  Version:
             Keywords:  mpeg         |  unspecified
  robustness                         |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 When decoding australian MPEG2 video broadcast with many stream errors the
 decoder causes a memory error crash because the index into the scan table
 is far outside the array.
 The simple dirty fix is to mask the index into the scan table to a value
 between 0 and 63 to prevent memory access error.
 The attached diff files documents the required patch.
 As a result the robustness of the decoder has increased.

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/764>
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