SNA 3.0 Service Pack 2 Hang or Access Violation in SNA Server or SnaBase (175271)

SYMPTOMS

After you upgrade to Microsoft SNA Server 3.0 Service Pack 2, one of the following symptoms may occur while the server is running:

Users who have active sessions may find their computer suddenly hangs or stops responding (3270 users may receive perpetual XCLOCK), and new user connection attempts to either the SnaBase or SNA Server service may fail.
The SnaBase or SNA Server service may terminate unexpectedly with the following error messages:

Windows NT application event log error:
Event: 624
Source: SNA Server (or SnaBase)
Description: Creating dump file C:\SNA\traces\snadump.log for
Snaservr.exe [or snabase.exe]
Also, an <Ntroot>\Drwtsn32.log entry may be created, indicating the following failure:
Application exception occurred:
App: snaservr.DBG (pid=<process ID>)
When: <date and time>
Exception number: c0000005 (access violation)
The fault entry indicated in routine ntdll!RtlAllocateHeap, or ntdll!RtlDestroyHeap.

CAUSE

In SNA Server 3.0 Service Pack 2, client logon requests are now handled from multiple threads within the SnaBase or SNA Server service. If two concurrent client logon requests occur that both use the LSA authentication method (that is, Windows 3.x clients, or Windows NT services that run under the local system account), the SnaBase or SNA Server memory heap may become corrupted. This occurs because LSA logon is not thread-safe, so two concurrent LSA logon requests from the same process can result in memory corruption.

STATUS

Microsoft has confirmed this to be a problem in SNA Server version 3.0 Service Pack 2.

This problem was corrected in the latest SNA Server version 3.0 U.S. Service Pack. For information on obtaining this Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K