[FFmpeg-trac] #8325(undetermined:new): outside the range of representable values of type 'unsigned long' at libavcodec/ratecontrol.c:966

FFmpeg trac at avcodec.org
Tue Oct 22 10:48:28 EEST 2019


#8325: outside the range of representable values of type 'unsigned long' at
libavcodec/ratecontrol.c:966
-------------------------------------+-------------------------------------
             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 an outside the range of representable values of type 'unsigned
 long' at libavcodec/ratecontrol.c:966

 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 framerate -target vcd -loglevel 0 -c
 wmv1 tmp.wsd

 ffmpeg version N-95517-g0b8956b25c 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

 {{{
 libavcodec/ratecontrol.c:966:37: runtime error: -443679 is outside the
 range of representable values of type 'unsigned long'

 Thread 1 "ffmpeg_g" hit Breakpoint 1, 0x00000000004288b0 in
 __ubsan::ScopedReport::~ScopedReport() ()
 (gdb) bt
 #0  0x00000000004288b0 in __ubsan::ScopedReport::~ScopedReport() ()
 #1  0x000000000042a4e6 in handleFloatCastOverflow(void*, unsigned long,
 __ubsan::ReportOptions) ()
 #2  0x000000000042cd11 in __ubsan_handle_float_cast_overflow ()
 #3  0x0000000002fa96f3 in ff_rate_estimate_qscale (s=0x93d8940, dry_run=0)
 at libavcodec/ratecontrol.c:966
 #4  0x0000000002be940f in estimate_qp (s=0x93d8940, dry_run=0) at
 libavcodec/mpegvideo_enc.c:3607
 #5  0x0000000002bde6a1 in encode_picture (s=0x93d8940, picture_number=30)
 at libavcodec/mpegvideo_enc.c:3807
 #6  0x0000000002bc347a in ff_mpv_encode_picture (avctx=0x93ceb40,
 pkt=0x9410d40, pic_arg=<optimized out>,
     got_packet=0x7fffffffc2a4) at libavcodec/mpegvideo_enc.c:1868
 #7  0x0000000001fe242f in avcodec_encode_video2 (avctx=0x93ceb40,
 avpkt=<optimized out>, frame=<optimized out>,
     got_packet_ptr=0x7fffffffc2a4) at libavcodec/encode.c:302
 #8  0x0000000001fe4160 in do_encode (avctx=0x93ceb40, frame=0x9449f80,
 got_packet=0x7fffffffc2a4) at libavcodec/encode.c:371
 #9  0x0000000001fe3cda in avcodec_send_frame (avctx=0x93ceb40,
 frame=0x9449f80) at libavcodec/encode.c:420
 #10 0x00000000004c51f8 in do_video_out (of=0x93cce80, ost=<optimized out>,
 next_picture=<optimized out>,
     sync_ipts=28.500007629394535) at fftools/ffmpeg.c:1287
 #11 0x00000000004c0f2b in reap_filters (flush=0) at fftools/ffmpeg.c:1504
 #12 0x000000000048c3d5 in transcode_from_filter (graph=0x93c7700,
 best_ist=<optimized out>) at fftools/ffmpeg.c:4533
 #13 transcode_step () at fftools/ffmpeg.c:4606
 #14 transcode () at fftools/ffmpeg.c:4682
 #15 0x0000000000487dc4 in main (argc=13, argv=<optimized out>) at
 fftools/ffmpeg.c:4884

 }}}
 Please confirm.
 Thanks

--
Ticket URL: <https://trac.ffmpeg.org/ticket/8325>
FFmpeg <https://ffmpeg.org>
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