In all cases where any county has bid in and purchased real estate in any tax foreclosure action and the same has been conveyed to such county by the sheriff prior to January 1, 1948, and the proceedings by which such county purchased and received a conveyance of such real estate were not in compliance with the applicable existing law at the time the same were had, such proceedings are hereby validated and confirmed; and all deeds executed by any county clerk conveying any such real estate so acquired by any county which have been recorded in the office of the register of deeds of the proper county prior to July 1, 1948, are hereby validated and confirmed and the title conveyed by any such deed is hereby declared merchantable to the extent of the interest therein conveyed: Provided, That any person desiring to present proof of the invalidity or partial invalidity of any such deed shall have one year after the effective date of this act within which to bring proceedings attacking such deed.