Null pointer dereference vulnerability in ifilter_bank(libfaad/filtbank.c:246)

[fantasy7082]

Hi, i found a null pointer dereference bug in Freeware Advanced Audio Decoder 2 (FAAD2) 2.8.8. It crashed in function ifilter_bank.the details are below(ASAN):

./faad faad_res/002-null-point-filtbank_246 -o out.wav
 *********** Ahead Software MPEG-4 AAC Decoder V2.8.8 ******************

 Build: Dec 13 2018
 Copyright 2002-2004: Ahead Software AG
 http://www.audiocoding.com
 bug tracking: https://sourceforge.net/p/faac/bugs/
 Floating point version

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License.

 **************************************************************************

faad_res/002-null-point-filtbank_246 file info:
ADTS, 0.043 sec, 37 kbps, 48000 Hz

  ---------------------
 | Config:  3 Ch       |
  ---------------------
 | Ch |    Position    |
  ---------------------
 | 00 | Left front     |
 | 01 | Right front    |
 | 02 | Unknown        |
  ---------------------

ASAN:SIGSEGV faad_res/002-null-point-filtbank_246.
=================================================================
==7062==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7fe67b9599f6 bp 0x7fff60c60600 sp 0x7fff60c5e510 T0)
    #0 0x7fe67b9599f5 in ifilter_bank /root/faad2_asan/libfaad/filtbank.c:246
    #1 0x7fe67b99519d in reconstruct_channel_pair /root/faad2_asan/libfaad/specrec.c:1258
    #2 0x7fe67b99b823 in channel_pair_element /root/faad2_asan/libfaad/syntax.c:759
    #3 0x7fe67b999cbf in decode_cpe /root/faad2_asan/libfaad/syntax.c:402
    #4 0x7fe67b99a398 in raw_data_block /root/faad2_asan/libfaad/syntax.c:448
    #5 0x7fe67b9549c3 in aac_frame_decode /root/faad2_asan/libfaad/decoder.c:990
    #6 0x7fe67b954566 in NeAACDecDecode /root/faad2_asan/libfaad/decoder.c:821
    #7 0x40f8ae in decodeAACfile /root/faad2_asan/frontend/main.c:679
    #8 0x411dd4 in faad_main /root/faad2_asan/frontend/main.c:1323
    #9 0x411fe5 in main /root/faad2_asan/frontend/main.c:1366
    #10 0x7fe67b58c82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #11 0x401aa8 in _start (/usr/local/faad-asan/bin/faad+0x401aa8)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /root/faad2_asan/libfaad/filtbank.c:246 ifilter_bank
==7062==ABORTING

POC FILE:https://github.com/fantasy7082/image_test/blob/master/002-null-point-filtbank_246

[hlef]

This issue has been assigned CVE-2018-20198.

Same underlying issue as #26.

@fabiangreffrath : fixed by 466b01d.

[fabiangreffrath]

Closing, thanks!