[FFmpeg-trac] #8270(undetermined:new): left shift of negative value at libavfilter/vf_mestimate.c:109

FFmpeg trac at avcodec.org
Mon Oct 14 04:50:41 EEST 2019


#8270: left shift of negative value at libavfilter/vf_mestimate.c:109
-------------------------------------+-------------------------------------
             Reporter:  Suhwan       |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:  ubsan        |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 There're 2 left shift of negative value at libavfilter/vf_mestimate.c:109
 I compiled ffmpeg with "--toolchain=clang-usan" to check the undefined-
 behaviours and attached log file.
 How to reproduce:
 {{{
 % ffmpeg_g -y -i $PoC -filter_complex mestimate -target dv50 -loglevel 0
 tmp.siff

 ffmpeg version N-95343-ge835a9d302 Copyright (c) 2000-2019 the FFmpeg
 developers
 built with clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
 configuration: --cc=clang --cxx=clang++ --ld=clang --enable-debug
 --toolchain=clang-usan
 }}}

 Here's UBSAN log

 {{{
 libavfilter/vf_mestimate.c:109:107: runtime error: left shift of negative
 value -1
 SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
 libavfilter/vf_mestimate.c:109:107 in
 libavfilter/vf_mestimate.c:109:148: runtime error: left shift of negative
 value -1
 SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
 libavfilter/vf_mestimate.c:109:148 in
 }}}
 Please confirm.
 Thanks

--
Ticket URL: <https://trac.ffmpeg.org/ticket/8270>
FFmpeg <https://ffmpeg.org>
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