[FFmpeg-trac] #8259(undetermined:reopened): A use-after-free bug in libavcodec/utils.c

FFmpeg trac at avcodec.org
Sun Oct 13 17:03:03 EEST 2019

#8259: A use-after-free bug in libavcodec/utils.c
             Reporter:  wurongxin    |                    Owner:
                 Type:  defect       |                   Status:  reopened
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  3.4.6        |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
Changes (by wurongxin):

 * status:  closed => reopened
 * resolution:  invalid =>


 Replying to [comment:1 mkver]:
 > Having a dangling pointer and using it in a function call does not
 constitute a use-after-free; for this, one would have to try to access the
 (invalid) data at the place where the pointer points to.

 I don't think this is a safe operation and a good practice to write the
 code like that way. Moreover, it totally matches the definition of use-
 after-free. A very simple solution would be to swap the Line 104 and 105.
 Please consider it carefully. BTW, this happens in libavcodec, why you
 label the component as undetermined?

Ticket URL: <https://trac.ffmpeg.org/ticket/8259#comment:2>
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