libao memory corruption vulnerability
================
Author : qflb.wu
===============


Introduction:
=============
Libao is a cross-platform audio library that allows programs to output audio using a simple API on a wide variety of platforms.


Affected version:
=====
1.2.0


Vulnerability Description:
==========================
the _tokenize_matrix function in audio_out.c in Xiph.Org libao 1.2.0 can cause a denial of service(memory corruption) via a crafted mp3 file.


I found this bug when I test mpg321 0.3.2 which used the libao library.


./mpg321 libao_1.2.0_memory_corruption.mp3


----debug info:----
Program received signal SIGSEGV, Segmentation fault.
_int_malloc (av=av@entry=0x7ffff6f7f760 <main_arena>, bytes=bytes@entry=3)
    at malloc.c:3740
3740malloc.c: No such file or directory.
(gdb) bt
#0  _int_malloc (av=av@entry=0x7ffff6f7f760 <main_arena>, bytes=bytes@entry=3)
    at malloc.c:3740
#1  0x00007ffff6c442cc in __libc_calloc (n=<optimized out>, 
    elem_size=<optimized out>) at malloc.c:3219
#2  0x00007ffff728e189 in _tokenize_matrix () from /usr/local/lib/libao.so.4
#3  0x00007ffff728e607 in _matrix_to_channelmask ()
   from /usr/local/lib/libao.so.4
#4  0x00007ffff72906f2 in _open_device () from /usr/local/lib/libao.so.4
#5  0x000000000040a6aa in open_ao_playdevice (header=header@entry=0x624af8)
    at ao.c:411
#6  0x0000000000407e50 in output (data=<optimized out>, header=0x624af8, 
    pcm=0x627f44) at mad.c:974
#7  0x00007ffff749a85c in run_sync (decoder=0x7fffffffbc40) at decoder.c:439
#8  0x00007ffff749ab38 in mad_decoder_run (
    decoder=decoder@entry=0x7fffffffbc40, 
    mode=mode@entry=MAD_DECODER_MODE_SYNC) at decoder.c:557
#9  0x0000000000403d5d in main (argc=<optimized out>, argv=<optimized out>)
    at mpg321.c:1092
(gdb) 


POC:
libao_1.2.0_memory_corruption.mp3
CVE:
CVE-2017-11548


Proof of Concept:
https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/42400.zip