Stop 0x0A When NWNBLNK Accesses Memory in Free Pool

• Microsoft Windows NT Workstation version 3.51
• Microsoft Windows NT Server version 3.51

SYMPTOMS

Computers that use NWLink NetBIOS may experience blue stop screens with a bugcheck code of 0x0A: IRQL_NOT_LESS_OR_EQUAL.

Examination of a crashdump, or a live debug, usually reveals that the exception occurred in function KeAcquireSpinLock called from function HandleConnectionZero, and is caused by NWLNKNB accessing memory that is either in free pool or which has been acquired by another process.

CAUSE

Due to incorrect synchronization logic, there is an exposure in NWNBLNK that causes a bugcheck when multiple requests are processed for the same NWNBLNK connection. If one of the requests is a disconnect, in some rare circumstances the disconnect is completed first, freeing the memory structure used for the NWNBLNK connection structure. When processing of the remaining requests resume, a Stop 0x0A results when attempting to access the now freed (and possibly reused) connection structure.

Due to the nature of this problem it occurs very infrequently. When the problem does occur, it is most likely to be seen on faster computers, particularly on multi-processor computers, such as multi-processor DEC Alpha servers.

RESOLUTION

Apply the hotfix described below or upgrade to Windows NT 4.0.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.51. A supported fix is now available, but is not 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 Product Support Services for more information.