[FFmpeg-trac] #2444(avfilter:open): memory corruption/core dump using alpha overlay in current git ffmpeg

FFmpeg trac at avcodec.org
Sun Apr 7 15:34:21 CEST 2013


#2444: memory corruption/core dump using alpha overlay in current git ffmpeg
-------------------------------------+-------------------------------------
             Reporter:  MarkZV       |                    Owner:
                 Type:  defect       |                   Status:  open
             Priority:  important    |                Component:  avfilter
              Version:  git-master   |               Resolution:
             Keywords:  crash        |               Blocked By:
  regression                         |  Reproduced by developer:  1
             Blocking:               |
Analyzed by developer:  1            |
-------------------------------------+-------------------------------------
Changes (by Cigaes):

 * analyzed:  0 => 1


Comment:

 I believe the bug is in {{{vf_mp}}}: the {{{filter_frame}}} wraps the
 refcounted data planes from the incoming frame into a {{{mp_image_t}}},
 then {{{ff_vf_next_put_image}}} takes the data planes from the
 {{{mp_image_t}}} and wraps them into a new (refcounted) frame.

 With eq2, the planes 1 and 2 are passed unchanged, that means the data
 planes will end up wrapped into two distinct refcounted buffers, which is
 not good.

 Note that commit b0012de only changes the order various parts are called:
 things working before that would only be a fragile coincidence.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2444#comment:3>
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