The ETS Math Review is designed to familiarize you with the major quant concepts that you'll need to know for the GRE. It's not all-encompassing, but it does give you a really solid foundation as to what you should expect on test day! Here's what ETS has to say about its purpose:
This Math Review will familiarize you with the mathematical skills and concepts that are important to understand in order to solve problems and to reason quantitatively on the Quantitative Reasoning measure of the GRE Revised General Test. The following material includes many definitions, properties, and examples, as well as a set of exercises (with answers) at the end of each review section. Note, however, that this review is not intended to be all-inclusive -- there may be some concepts on the test that are not explicitly presented in this review.
You can find and download the Math Review right here, or you can also find it in the Official Guide to the GRE!