left shift of negative value at libavfilter/vf_edgedetect.c:219

[Suhwan]

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 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_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 libavfilter/vf_edgedetect.c:219
#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 libavfilter/vf_edgedetect.c:372
#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 libavfilter/avfilter.c:1232
#8  ff_filter_activate_default (filter=<optimized out>) at libavfilter/avfilter.c:1281
#9  ff_filter_activate (filter=<optimized out>) at libavfilter/avfilter.c:1443
#10 0x00000000005f42bf in push_frame (graph=0x93ae5c0) at libavfilter/buffersrc.c:187
#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 fftools/ffmpeg.c:2260
#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 fftools/ffmpeg.c:4508
#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 fftools/ffmpeg.c:4884

Please confirm.
Thanks

[Suhwan]

poc