[FFmpeg-trac] #8287(undetermined:new): left shift of negative value at libavfilter/vf_edgedetect.c:219

FFmpeg trac at avcodec.org
Wed Oct 16 18:37:09 EEST 2019

#8287: left shift of negative value at libavfilter/vf_edgedetect.c:219
             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 is a left shift of negative value at libavfilter/vf_edgedetect.c:219

 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 edgedetect -target dvd -loglevel 0
 -map 0 tmp.gxf

 ffmpeg version N-95399-g1a0c584abc Copyright (c) 2000-2019 the FFmpeg
 built with clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
 configuration: --cc=clang --cxx=clang++ --ld=clang --enable-debug

 Here's UBSAN log

 libavfilter/vf_edgedetect.c:219:12: runtime error: left shift of negative
 value -273

 Thread 1 "ffmpeg_g" hit Breakpoint 1, 0x00000000004288b0 in
 __ubsan::ScopedReport::~ScopedReport() ()
 (gdb) bt
 #0  0x00000000004288b0 in __ubsan::ScopedReport::~ScopedReport() ()
 #1  0x000000000042a9a0 in
 handleShiftOutOfBoundsImpl(__ubsan::ShiftOutOfBoundsData*, unsigned long,
 unsigned long, __ubsan::ReportOptions) ()
 #2  0x000000000042cb41 in __ubsan_handle_shift_out_of_bounds ()
 #3  0x0000000000951d7a in get_rounded_direction (gx=727, gy=-273) at
 #4  sobel (w=<optimized out>, dst=<optimized out>, dst_linesize=<optimized
 out>, dir=<optimized out>, dir_linesize=<optimized out>, src=<optimized
 out>, src_linesize=<optimized out>,
     h=<optimized out>) at libavfilter/vf_edgedetect.c:251
 #5  filter_frame (inlink=<optimized out>, in=<optimized out>) at
 #6  0x00000000005cfe9d in ff_filter_frame_framed (link=<optimized out>,
 frame=0x0) at libavfilter/avfilter.c:1084
 #7  ff_filter_frame_to_filter (link=<optimized out>) at
 #8  ff_filter_activate_default (filter=<optimized out>) at
 #9  ff_filter_activate (filter=<optimized out>) at
 #10 0x00000000005f42bf in push_frame (graph=0x93ae5c0) at
 #11 av_buffersrc_add_frame_internal (ctx=<optimized out>, frame=0x93c6bc0,
 flags=<optimized out>) at libavfilter/buffersrc.c:261
 #12 0x00000000005f2e7e in av_buffersrc_add_frame_flags (ctx=0x93e07c0,
 frame=0x93c6bc0, flags=4) at libavfilter/buffersrc.c:170
 #13 0x00000000004cad60 in ifilter_send_frame (ifilter=<optimized out>,
 frame=<optimized out>) at fftools/ffmpeg.c:2186
 #14 send_frame_to_filters (ist=0x93b2f40, decoded_frame=0x93c6bc0) at
 #15 0x00000000004a07bc in decode_video (ist=<optimized out>,
 pkt=<optimized out>, got_output=<optimized out>, duration_pts=<optimized
 out>, eof=<optimized out>, decode_failed=<optimized out>)
     at fftools/ffmpeg.c:2459
 #16 process_input_packet (ist=<optimized out>, pkt=<optimized out>,
 no_eof=<optimized out>) at fftools/ffmpeg.c:2613
 #17 0x00000000004bf0f0 in process_input (file_index=<optimized out>) at
 #18 0x000000000048d5eb in transcode_step () at fftools/ffmpeg.c:4628
 #19 transcode () at fftools/ffmpeg.c:4682
 #20 0x0000000000487da4 in main (argc=15, argv=<optimized out>) at

 Please confirm.

Ticket URL: <https://trac.ffmpeg.org/ticket/8287>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker

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