heap overflow in ffmpeg(add_input_streams fftools/ffmpeg_demux.c:691)

[Youngseok Choi]

Our fuzzer found a new heap overflow bug in ffmpeg.

Command Input

ffmpeg -tag F -pattern_type 1 -i ?.y

Interestingly, there is no input file. Only command line arguments lead ffmpeg to crash.

Command Output

ffmpeg version N-110167-g97c95961f0 Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --prefix=/home/youngseok/subjects/latest_asan_install/ffmpeg --extra-cflags='-fsanitize=address -g -O0' --extra-cxxflags='-fsanitize=address -g -O0' --extra-ldflags='-fsanitize=address -g -O0' --disable-optimizations --disable-stripping
  libavutil      58.  5.100 / 58.  5.100
  libavcodec     60.  9.100 / 60.  9.100
  libavformat    60.  4.101 / 60.  4.101
  libavdevice    60.  2.100 / 60.  2.100
  libavfilter     9.  5.100 /  9.  5.100
  libswscale      7.  2.100 /  7.  2.100
  libswresample   4. 11.100 /  4. 11.100
[rawvideo @ 0x619000000580] Invalid pixel format.
[image2 @ 0x617000000080] Failed to open codec in avformat_find_stream_info
[image2 @ 0x617000000080] Could not open file : ?.y
[rawvideo @ 0x619000000580] Invalid pixel format.
[image2 @ 0x617000000080] Failed to open codec in avformat_find_stream_info
[image2 @ 0x617000000080] Could not find codec parameters for stream 0 (Video: rawvideo, none): unspecified size
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options

Sanitizer Dump

==19936==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000000b0 at pc 0x555555a8dd9e bp 0x7fffffffc820 sp 0x7fffffffc810
READ of size 4 at 0x6020000000b0 thread T0
    #0 0x555555a8dd9d in add_input_streams fftools/ffmpeg_demux.c:691
    #1 0x555555a96932 in ifile_open fftools/ffmpeg_demux.c:1165
    #2 0x555555adb403 in open_files fftools/ffmpeg_opt.c:1244
    #3 0x555555adb778 in ffmpeg_parse_options fftools/ffmpeg_opt.c:1283
    #4 0x555555b195ba in main fftools/ffmpeg.c:4165
    #5 0x7ffff5601c86 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21c86)
    #6 0x555555a84499 in _start (/home/youngseok/subjects/latest_asan_install/ffmpeg/bin/ffmpeg+0x530499)

0x6020000000b2 is located 0 bytes to the right of 2-byte region [0x6020000000b0,0x6020000000b2)
allocated by thread T0 here:
    #0 0x7ffff6ef6f30 in realloc (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xdef30)
    #1 0x555558d1133a in av_realloc libavutil/mem.c:162
    #2 0x555558d1207d in av_strdup libavutil/mem.c:275
    #3 0x555555ae2178 in write_option fftools/cmdutils.c:282
    #4 0x555555ae31c4 in parse_optgroup fftools/cmdutils.c:405
    #5 0x555555adb2d2 in open_files fftools/ffmpeg_opt.c:1235
    #6 0x555555adb778 in ffmpeg_parse_options fftools/ffmpeg_opt.c:1283
    #7 0x555555b195ba in main fftools/ffmpeg.c:4165
    #8 0x7ffff5601c86 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21c86)

Environment

Built with address sanitizer.

ffmpeg version N-110167-g97c95961f0 Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --prefix=/home/youngseok/subjects/latest_asan_install/ffmpeg --extra-cflags='-fsanitize=address -g -O0' --extra-cxxflags='-fsanitize=address -g -O0' --extra-ldflags='-fsanitize=address -g -O0' --disable-optimizations --disable-stripping

[elenril]

Fixed in 89c9a3ac3542.

Backported to:

6.0 as 8f61cbf1b92
5.1 as 1e413487bf8
5.0 as e30302c6363