gameboy emulation causes invalid memory read

[Wohlstand]

Original report by Hanno Böck (Bitbucket: [Hanno Böck](https://bitbucket.org/Hanno Böck), ).

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When compiling game-music-emu with address sanitizer and trying to play a gameboy music file (I tested with this one [1]) I see an invalid memory read in version 0.6.1.

The reason is this code:

#!c

    static unsigned char const initial_wave [] = {
        0x84,0x40,0x43,0xAA,0x2D,0x78,0x92,0x3C, // wave table
        0x60,0x59,0x59,0xB0,0x34,0xB8,0x2E,0xDA
    };
    memcpy( wave.wave, initial_wave, sizeof wave.wave );

It seems "sizeof wave.wave" is 32, however the initial_wave array is only 16 bytes. Therefore this overreads. I think just changing "sizeof wave.wave" to "16" should fix this (at least I can play the file after that), but this should probably be reviewed by someone familiar with the code.

[1] http://www.zophar.net/music/gameboy-gbs/102-dalmatians-puppies-to-the-rescue

Here's the full error message from address sanitizer:

==7807==ERROR: AddressSanitizer: global-buffer-overflow on address 0x000000632c90 at pc 0x0000004c0bb5 bp 0x7fffea986480 sp 0x7fffea985c30
READ of size 32 at 0x000000632c90 thread T0
    #0 0x4c0bb4 in __asan_memcpy (/mnt/ram/game-music-emu-0.6.1/b/player/gme_player+0x4c0bb4)
    #1 0x5a7a1d in Gb_Apu::reset() /mnt/ram/game-music-emu-0.6.1/gme/Gb_Apu.cpp:126:2
    #2 0x5a7a1d in Gb_Apu::Gb_Apu() /mnt/ram/game-music-emu-0.6.1/gme/Gb_Apu.cpp:48
    #3 0x52d58d in Gbs_Emu::Gbs_Emu() /mnt/ram/game-music-emu-0.6.1/gme/Gbs_Emu.cpp:26:10
    #4 0x52fb8f in new_gbs_emu() /mnt/ram/game-music-emu-0.6.1/gme/Gbs_Emu.cpp:100:54
    #5 0x519477 in gme_new_emu /mnt/ram/game-music-emu-0.6.1/gme/gme.cpp:197:19
    #6 0x519e2e in gme_open_file /mnt/ram/game-music-emu-0.6.1/gme/gme.cpp:174:19
    #7 0x514f1b in Music_Player::load_file(char const*) /mnt/ram/game-music-emu-0.6.1/player/Music_Player.cpp:78:2
    #8 0x5164be in main /mnt/ram/game-music-emu-0.6.1/player/player.cpp:88:24
    #9 0x7f3e27a39690 in __libc_start_main /var/tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
    #10 0x427898 in _start (/mnt/ram/game-music-emu-0.6.1/b/player/gme_player+0x427898)

0x000000632c90 is located 48 bytes to the left of global variable '<string literal>' defined in '/mnt/ram/game-music-emu-0.6.1/gme/Gb_Apu.cpp:125:12' (0x632cc0) of size 5
  '<string literal>' is ascii string '%i 
'
0x000000632c90 is located 0 bytes to the right of global variable 'initial_wave' defined in '/mnt/ram/game-music-emu-0.6.1/gme/Gb_Apu.cpp:122:29' (0x632c80) of size 16

[Wohlstand]

Original comment by Hanno Böck (Bitbucket: [Hanno Böck](https://bitbucket.org/Hanno Böck), ).

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proposed patch

[Wohlstand]

Original comment by Michael Pyne (Bitbucket: mpyne, GitHub: mpyne).

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Duplicate of #5.

[Wohlstand]

Original comment by Michael Pyne (Bitbucket: mpyne, GitHub: mpyne).

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As noted this was already reported and fixed in issue #5, but it's good to see that ASan is able to detect this class of bug!