Exploit-DB #42258
Description: LAME 3.99.5 - 'II_step_one' Buffer Overflow
Type: dos
Platform: linux
Date: 2017-06-26
Author: Agostino Sarubbo

Exploit:
Description:
lame is a high quality MPEG Audio Layer III (MP3) encoder licensed under the LGPL.

Few notes before the details of this bug. Time ago a fuzz was done by Brian Carpenter and Jakub Wilk which posted the results on the debian bugtracker. In cases like this, when upstream is not active and people do not post on the upstream bugzilla is easy discover duplicates, so I downloaded all available testcases, and noone of the bug you will see on my blog is a duplicate of an existing issue. Upstream seems a bit dead, latest release was into 2011, so this blog post will probably forwarded on the upstream bugtracker just for the record.

The complete ASan output of the issue:

# lame -f -V 9 $FILE out.wav
==27479==ERROR: AddressSanitizer: global-buffer-overflow on address 0x7f598d317f20 at pc 0x7f598d2b246b bp 0x7ffe780cf310 sp 0x7ffe780cf308
READ of size 2 at 0x7f598d317f20 thread T0
    #0 0x7f598d2b246a in II_step_one /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/mpglib/layer2.c:144:36
    #1 0x7f598d2b246a in decode_layer2_frame /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/mpglib/layer2.c:375
    #2 0x7f598d29b377 in decodeMP3_clipchoice /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/mpglib/interface.c:611:13
    #3 0x7f598d298c13 in decodeMP3 /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/mpglib/interface.c:696:12
    #4 0x7f598d259092 in decode1_headersB_clipchoice /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/libmp3lame/mpglib_interface.c:149:11
    #5 0x7f598d25e94a in hip_decode1_headersB /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/libmp3lame/mpglib_interface.c:436:16
    #6 0x7f598d25e94a in hip_decode1_headers /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/libmp3lame/mpglib_interface.c:379
    #7 0x51e984 in lame_decode_fromfile /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/frontend/get_audio.c:2089:11
    #8 0x51e984 in read_samples_mp3 /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/frontend/get_audio.c:877
    #9 0x51e984 in get_audio_common /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/frontend/get_audio.c:785
    #10 0x51e4fa in get_audio /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/frontend/get_audio.c:688:16
    #11 0x50f776 in lame_encoder_loop /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/frontend/lame_main.c:456:17
    #12 0x50f776 in lame_encoder /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/frontend/lame_main.c:531
    #13 0x50c43f in lame_main /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/frontend/lame_main.c:707:15
    #14 0x510793 in c_main /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/frontend/main.c:470:15
    #15 0x510793 in main /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/frontend/main.c:438
    #16 0x7f598be51680 in __libc_start_main /tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
    #17 0x41c998 in _init (/usr/bin/lame+0x41c998)

0x7f598d317f20 is located 0 bytes to the right of global variable 'alloc_2' defined in '/var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/mpglib/l2tables.h:118:24' (0x7f598d317de0) of size 320
SUMMARY: AddressSanitizer: global-buffer-overflow /var/tmp/portage/media-sound/lame-3.99.5-r1/work/lame-3.99.5/mpglib/layer2.c:144:36 in II_step_one
Shadow bytes around the buggy address:
  0x0febb1a5af90: 00 00 00 00 00 00 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
  0x0febb1a5afa0: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
  0x0febb1a5afb0: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 00 00 00 00
  0x0febb1a5afc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0febb1a5afd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0febb1a5afe0: 00 00 00 00[f9]f9 f9 f9 f9 f9 f9 f9 00 00 00 00
  0x0febb1a5aff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0febb1a5b000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0febb1a5b010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0febb1a5b020: 00 00 00 00 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
  0x0febb1a5b030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==27479==ABORTING
Affected version:
3.99.5

Fixed version:
N/A

Commit fix:
N/A

Credit:
This bug was discovered by Agostino Sarubbo of Gentoo.

CVE:
N/A

Reproducer:
https://github.com/asarubbo/poc/blob/master/00290-lame-globaloverflow-II_step_one

Timeline:
2017-06-01: bug discovered
2017-06-17: blog post about the issue

Note:
This bug was found with American Fuzzy Lop.


Proof of Concept:
https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/42258.zip