A chainsaw is dangerous used in any way if you do not have instruction or experience when picking one up. I understand the intuitive assumption of "always cut away from yourself"- which makes sense with most saws where the saw is in motion and the wood is stationary, like a circular saw. In most cases with these saws, it's a good idea to cut away from you.
However, with a chainsaw, after receiving proper instruction, you can cut from most angles and directions, as it is designed to do just that. As other posters mentioned, making a cut at least halfway through from the bottom up is common, and often the safest way to cut a log that is parallel to the ground. It helps to avoid the saw binding up in the wood if/when the log starts to bend inward on the cut. To cut down a tree, often you will cut a wedge out on the side you want it to fall from, and then cut forward from the back to the wedge.
I learned safe and efficient chainsaw work from a tree service professional who visited my firehouse to teach us.