[FFmpeg-trac] #6388(avutil:new): MSan: use-of-uninitialized-value in ff_get_cpu_flags_x86()

[FFmpeg]

#6388: MSan: use-of-uninitialized-value in ff_get_cpu_flags_x86()
--------------------------------+--------------------------------------
             Reporter:  tsmith  |                     Type:  defect
               Status:  new     |                 Priority:  normal
            Component:  avutil  |                  Version:  git-master
             Keywords:          |               Blocked By:
             Blocking:          |  Reproduced by developer:  0
Analyzed by developer:  0       |
--------------------------------+--------------------------------------
 How to reproduce:
 Built with MSan or run with Valgrind
 {{{
 % ffmpeg -f ivf -i <test_case> -f null -
 ffmpeg version N-86050-g0fbc7a2 Copyright (c) 2000-2017 the FFmpeg
 developers
   built with clang version 3.8.0-2ubuntu4 (tags/RELEASE_380/final)
   configuration: --cc=clang --cxx=clang++ --disable-libxcb --disable-xlib
 --disable-logging --disable-ffprobe --disable-ffplay --disable-sdl2
 --disable-ffserver --disable-doc --disable-pthreads --disable-network
 --disable-d3d11va --disable-dxva2 --disable-vaapi --disable-vda --disable-
 vdpau --disable-stripping --disable-runtime-cpudetect --disable-postproc
 --disable-securetransport --disable-iconv --disable-swscale --disable-
 avdevice --disable-videotoolbox --disable-everything --enable-
 encoder=wrapped_avframe --disable-lzma --enable-protocol='file,pipe'
 --enable-muxer=null --enable-demuxer=ivf --enable-parser=vp9 --enable-
 decoder=vp9 --disable-pic

 % ffmpeg -f ivf -i <test_case> -f null -
 ffmpeg version N-86050-g0fbc7a2 Copyright (c) 2000-2017 the FFmpeg
 developers
   built with clang version 3.8.0-2ubuntu4 (tags/RELEASE_380/final)
   configuration: --cc=clang --cxx=clang++ --disable-libxcb --disable-xlib
 --disable-logging --disable-ffprobe --disable-ffplay --disable-sdl2
 --disable-ffserver --disable-doc --disable-pthreads --disable-network
 --disable-d3d11va --disable-dxva2 --disable-vaapi --disable-vda --disable-
 vdpau --disable-stripping --disable-runtime-cpudetect --disable-postproc
 --disable-securetransport --disable-iconv --disable-swscale --disable-
 avdevice --disable-videotoolbox --disable-everything --enable-
 encoder=wrapped_avframe --disable-lzma --enable-protocol='file,pipe'
 --enable-muxer=null --enable-demuxer=ivf --enable-parser=vp9 --enable-
 decoder=vp9 --disable-pic

 ==21976==WARNING: MemorySanitizer: use-of-uninitialized-value
     #0 0xea6be0 in ff_get_cpu_flags_x86 FFmpeg/libavutil/x86/cpu.c:106:9
     #1 0xdd3651 in get_cpu_flags FFmpeg/libavutil/cpu.c:59:16
     #2 0xdd3651 in av_get_cpu_flags FFmpeg/libavutil/cpu.c:93
     #3 0xc2d18b in ff_vp9dsp_init_x86
 FFmpeg/libavcodec/x86/vp9dsp_init.c:230:17
     #4 0x7bfbe0 in update_size FFmpeg/libavcodec/vp9.c:205:9
     #5 0x7bfbe0 in decode_frame_header FFmpeg/libavcodec/vp9.c:645
     #6 0x7a77d8 in vp9_decode_frame FFmpeg/libavcodec/vp9.c:1113:16
     #7 0x744fdc in decode_simple_internal
 FFmpeg/libavcodec/decode.c:417:15
     #8 0x744fdc in decode_simple_receive_frame
 FFmpeg/libavcodec/decode.c:620
     #9 0x744fdc in decode_receive_frame_internal
 FFmpeg/libavcodec/decode.c:638
     #10 0x741daa in avcodec_send_packet FFmpeg/libavcodec/decode.c:678:15
     #11 0x6edb60 in try_decode_frame FFmpeg/libavformat/utils.c:3004:19
     #12 0x6d98dc in avformat_find_stream_info
 FFmpeg/libavformat/utils.c:3821:9
     #13 0x4baedc in open_input_file FFmpeg/ffmpeg_opt.c:1013:11
     #14 0x4b608c in open_files FFmpeg/ffmpeg_opt.c:3214:15
     #15 0x4b521d in ffmpeg_parse_options FFmpeg/ffmpeg_opt.c:3254:11
     #16 0x525f67 in main FFmpeg/ffmpeg.c:4771:11
     #17 0x7fab6e3dd82f in __libc_start_main /build/glibc-
 9tT8Do/glibc-2.23/csu/../csu/libc-start.c:291
     #18 0x41a6a8 in _start (FFmpeg/ffmpeg+0x41a6a8)

   Uninitialized value was created by an allocation of 'max_std_level' in
 the stack frame of function 'ff_get_cpu_flags_x86'
     #0 0xea5740 in ff_get_cpu_flags_x86 FFmpeg/libavutil/x86/cpu.c:91

 built on Ubuntu 16.04 x64 with clang 3.8
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6388>
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