ParquetSharp: Possible Stack Overflow When Reading a ParquetFile with Large Decimal Type Width

DecimalConverter.ReadDecimal makes a stackalloc using what might be an attacker-supplied value. If an attacker declares a decimal column with some unreasonable width, this could lead to a stack overflow. In a service environment, this would potentially take down a service.

This affects applications using ParquetSharp to read untrusted Parquet files in a network service.