The only restriction may be if you were on the mortgage. Read the short sale paperwork for restrictions. If you wee not on the mortgage, you should have no liability to the amount shorted and there for no problems buying, if you were on the mortgage, then have a lawyer read everything to make sure.
You should be able to buy it, however I would recommend you contact an attorney since some short sales may have an issue with the signed affidavit of an arms length transaction just to make sure you were not required to sign it, sometimes the buyer who now is the seller needs to keep property for a few months before he can sell it. So better to be safe than sorry and we as realtors can not give you any legal advice.