Yes, this is an ester hydrolysis.
A lactone is simply a cyclic ester, so the mechanism for its hydrolysis is exactly the same as for a noncyclic ester.
In this case, the structure of γ-butyrolactone is
The hydrolysis product is 4-hydroxybutanoic acid:
The alcohol group is acidic enough to react with
When you reduce the product, remember to add enough extra