GDB - I don't quite understand

#0  0x420807b6 in strcpy () from /lib/i686/libc.so.6
#1  0x080589b7 in profanity_filter (
    arg=0x8153200 "You're home planet is a little hard to get to right now.",
    out=0x8153200 "You're home planet is a little hard to get to right now.") at act_comm.c:446
#2  0x08059b7e in do_say (ch=0x8287858,
    argument=0x8153200 "You're home planet is a little hard to get to right now.")
    at act_comm.c:1056
#3  0x080deba9 in spec_newbie_pilot (ch=0x8287858) at special.c:160
#4  0x080ec279 in mobile_update () at update.c:689
#5  0x080eeaf5 in update_handler () at update.c:2227
#6  0x080922ff in game_loop () at comm.c:573
#7  0x08091b2c in main (argc=7, argv=0xbffffac4) at comm.c:236
#8  0x42017589 in __libc_start_main () from /lib/i686/libc.so.6

/*
 * Profanity Filter
 */
void profanity_filter( char * arg, char * out )
{
   char *nbuf, *tbuf, *p;
   bool change=TRUE;
   int x, v;

   nbuf = malloc(strlen(arg)+1);
   tbuf = malloc(strlen(arg)+1);

   strcpy(nbuf, strlower(arg));
   strcpy(tbuf, arg);

   while (change)
   {
      change = FALSE;

      for (x = 0; str_cmp(ignore_table[x], "$"); x++)
      {
	  if ( ( p = strstr(nbuf, ignore_table[x]) ) )
	  {
	    change = TRUE;
	    for (v = 0; v < strlen(ignore_table[x]); v++)
		*(p+v) = '.';
	  }
      }
   }

   change = TRUE;
   while (change)
   {
	change = FALSE;

	for (x = 0; strcmp(curse_table[x], "$"); x++)
	{
	   if ( ( p = strstr(nbuf, curse_table[x]) ) )
  	   {
		   change = TRUE;
		   for (v = 0; v < strlen(curse_table[x]); v++)
		     *(p+v) = '*';
           }
	}
   }

/*
 * Clonse *'s over to the real string
 */
for( x = 0; x < strlen( nbuf ); x++ )
{
	if ( nbuf[x] == '*' ) tbuf[x] = '*';
}

strcpy( out, tbuf );

free(nbuf);
free(tbuf);

return;

}