Buffer overruns due to incorrect InformationClass enum bounds checks

With many QueryInformation/SetInformation functions, we attempt check for valid InformationClass values, then access an array based on the (supposedly validated) value, e.g.

2161         if ((FileInformationClass >= FileMaximumInformation) ||

2162             !(IopQueryOperationLength[FileInformationClass]))

2163         {

2164             /* Invalid class */

2165             return STATUS_INVALID_INFO_CLASS;

2166         }

However, enum types are signed, which means these checks will not catch negative values and allow out-of-bounds access to the array. In many cases this allows user mode to crash the system or read kernel address space.