Combining control and Data in Machine-Level programs

Understanding pointers

• Pointers can also point to functions

…

GDB Debugger

Figure 3.39

Buffer overflow

• Consider this example program:

char *mygets(char *s){
    int c;
    char *dest = s;
    while ((c = getchar()) != '\n' && c != EOF)
        *dest++ = c;
    if (c == EOF && dest == s){
        return NULL;
    }
    *dest++ = '\0';
    return s;
}

void echo(){
    char buf[8];
    mygets(buf);
    puts(buf);
}