GF_Err smhd_Read(GF_Box *s, GF_BitStream *bs)
{
	GF_SoundMediaHeaderBox *ptr = (GF_SoundMediaHeaderBox *)s;
	ptr->balance = gf_bs_read_u16(bs);
	ptr->reserved = gf_bs_read_u16(bs);
	return GF_OK;
}

The product reads data past the end, or before the beginning, of the intended buffer.