Access Violation in RPCRT4.DLL When Pickling Buffered RPC Data

• Microsoft Windows NT Workstation version 4.0
• Microsoft Windows NT Server version 4.0

SYMPTOMS

Pickling, or serialization, is a Remote Procedure Call (RPC) process of marshaling data (encoding) and unmarshaling data (decoding) from buffers that you own. When you pickle and use wire_marshal, you may experience an Access Violation in Rpcrt4.dll. The wire_marshal attribute specifies a data type that will be used for transmission (the wire-type) instead of an application-specific data type (the userm-type). Each userm-type has a one- to-one correspondence with a wire-type that defines the wire representation of the type. You must supply routines to size the data for marshaling, to marshal and unmarshal the data, and to free memory.

NOTE: If there are embedded types in your data that are also defined with wire_marshal or user_marshal, you need to manage the servicing of those embedded types as well.

CAUSE

An uninitialized (NULL) buffer pointer is dereferenced to see if the underlying buffer was overwritten, causing an Access Violation.

RESOLUTION

To resolve this problem, obtain the following fix or wait for the next Windows NT service pack.

This fix should have the following time stamp:

   11/17/97  04:37p               312,080 Rpcrt4.dll (Intel)
   11/17/97  04:34p               550,672 Rpcrt4.dll (Alpha)

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. A supported fix is now available, but has not been fully regression tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.

Keywords          : kbbug4.00 kbfix4.00 NTSrvWkst
Version           : WinNT:4.0
Platform          : winnt
Issue type        : kbbug
Solution Type     : kbpatch