[FFmpeg-trac] #5169(avcodec:new): Memory leak in ebml_parse_elem()

[FFmpeg]

#5169: Memory leak in ebml_parse_elem()
---------------------------------+--------------------------------------
             Reporter:  tsmith   |                     Type:  defect
               Status:  new      |                 Priority:  normal
            Component:  avcodec  |                  Version:  git-master
             Keywords:           |               Blocked By:
             Blocking:           |  Reproduced by developer:  0
Analyzed by developer:  0        |
---------------------------------+--------------------------------------
 Summary of the bug:
 Memory leak triggered while processing a webm file.

 How to reproduce:
 {{{
 % ffmpeg -f webm -i test_case.webm -f null -

 ffmpeg version N-77870-gb58cfa6 Copyright (c) 2000-2016 the FFmpeg
 developers
   built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04)
   configuration: --cc=gcc --cxx=g++ --disable-libxcb --disable-xlib
 --disable-logging --disable-ffprobe --disable-ffplay --disable-sdl
 --disable-ffserver --disable-doc --disable-pthreads --disable-stripping
 --disable-runtime-cpudetect
   libavutil      55. 13.100 / 55. 13.100
   libavcodec     57. 22.100 / 57. 22.100
   libavformat    57. 21.101 / 57. 21.101
   libavdevice    57.  0.100 / 57.  0.100
   libavfilter     6. 24.100 /  6. 24.100
   libswscale      4.  0.100 /  4.  0.100
   libswresample   2.  0.101 /  2.  0.101

 ==21917==ERROR: LeakSanitizer: detected memory leaks

 Direct leak of 2688 byte(s) in 1 object(s) allocated from:
     #0 0x5029b0 in realloc /home/user/Desktop/llvm/projects/compiler-
 rt/lib/asan/asan_malloc_linux.cc:61
     #1 0x8e90ca in ebml_parse_elem
 /home/user/code/ffmpeg/libavformat/matroskadec.c:1075:19
     #2 0x8e83a1 in ebml_parse_id
 /home/user/code/ffmpeg/libavformat/matroskadec.c:954:12
     #3 0x8e83a1 in ebml_parse
 /home/user/code/ffmpeg/libavformat/matroskadec.c:970
     #4 0x8e9e27 in ebml_parse_nest
 /home/user/code/ffmpeg/libavformat/matroskadec.c:999:15
     #5 0x8e9e27 in ebml_parse_elem
 /home/user/code/ffmpeg/libavformat/matroskadec.c:1127
     #6 0x8e83a1 in ebml_parse_id
 /home/user/code/ffmpeg/libavformat/matroskadec.c:954:12
     #7 0x8e83a1 in ebml_parse
 /home/user/code/ffmpeg/libavformat/matroskadec.c:970
     #8 0x8dcf08 in matroska_read_header
 /home/user/code/ffmpeg/libavformat/matroskadec.c:2274:15
     #9 0xa86b59 in avformat_open_input
 /home/user/code/ffmpeg/libavformat/utils.c:482:20
     #10 0x53a764 in open_input_file
 /home/user/code/ffmpeg/ffmpeg_opt.c:950:11
     #11 0x538d01 in open_files /home/user/code/ffmpeg/ffmpeg_opt.c:2999:15
     #12 0x5385fc in ffmpeg_parse_options
 /home/user/code/ffmpeg/ffmpeg_opt.c:3036:11
     #13 0x55dd81 in main /home/user/code/ffmpeg/ffmpeg.c:4299:11
     #14 0x7fea45f1aec4 in __libc_start_main /build/buildd/eglibc-2.19/csu
 /libc-start.c:287

 Indirect leak of 32 byte(s) in 8 object(s) allocated from:
     #0 0x5029b0 in realloc /home/user/Desktop/llvm/projects/compiler-
 rt/lib/asan/asan_malloc_linux.cc:61
     #1 0x26e4e45 in av_realloc
 /home/user/code/ffmpeg/libavutil/mem.c:168:12
     #2 0x26e4e45 in av_strdup /home/user/code/ffmpeg/libavutil/mem.c:272
     #3 0x8e83a1 in ebml_parse_id
 /home/user/code/ffmpeg/libavformat/matroskadec.c:954:12
     #4 0x8e83a1 in ebml_parse
 /home/user/code/ffmpeg/libavformat/matroskadec.c:970
     #5 0x8e9e27 in ebml_parse_nest
 /home/user/code/ffmpeg/libavformat/matroskadec.c:999:15
     #6 0x8e9e27 in ebml_parse_elem
 /home/user/code/ffmpeg/libavformat/matroskadec.c:1127
     #7 0x8e83a1 in ebml_parse_id
 /home/user/code/ffmpeg/libavformat/matroskadec.c:954:12
     #8 0x8e83a1 in ebml_parse
 /home/user/code/ffmpeg/libavformat/matroskadec.c:970
     #9 0x8dcf08 in matroska_read_header
 /home/user/code/ffmpeg/libavformat/matroskadec.c:2274:15
     #10 0xa86b59 in avformat_open_input
 /home/user/code/ffmpeg/libavformat/utils.c:482:20
     #11 0x53a764 in open_input_file
 /home/user/code/ffmpeg/ffmpeg_opt.c:950:11
     #12 0x538d01 in open_files /home/user/code/ffmpeg/ffmpeg_opt.c:2999:15
     #13 0x5385fc in ffmpeg_parse_options
 /home/user/code/ffmpeg/ffmpeg_opt.c:3036:11
     #14 0x55dd81 in main /home/user/code/ffmpeg/ffmpeg.c:4299:11
     #15 0x7fea45f1aec4 in __libc_start_main /build/buildd/eglibc-2.19/csu
 /libc-start.c:287

 SUMMARY: AddressSanitizer: 2720 byte(s) leaked in 9 allocation(s).
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/5169>
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