Services for Macintosh May Cause a Problem When FastIoUnlockSingle() Returns FALSE

ID: Q242896

The information in this article applies to:

Microsoft Windows NT Server versions 4.0, 4.0 SP4, 4.0 SP5
Microsoft Windows NT Server, Enterprise Edition versions 4.0, 4.0 SP4, 4.0 SP5

SYMPTOMS

Services for Macintosh (SFM) may cause the computer to stop responding (hang) when FastIoUnlockSingle (a FastIO dispatch routine) returns FALSE. This corrupts the kernel memory and is sufficient to cause the computer to hang within a small number of input/output (I/O) operations. File systems and file system filter drivers sometimes need to prevent the FastIO path, usually because outstanding synchronization (for example, OpLocks and ByteRange locks) does not allow a simple pass-through of the operation to FsRtl or Cache Manager. Because the majority of FastIO routines are Boolean functions, the FastIO path can be disabled a FALSE response, thereby forcing an operation to take the Input/Output Request Packets (IRP) path instead.

Depending on how often a driver must disable FastIoUnlockSingle and the pattern of unlocks on a given computer, the problem may occur very frequently or very rarely.

CAUSE

Because SFM attempts to free the IRP twice in the completion routine and once in the routine that allocated the IRP, it causes Kernel-mode memory corruption. This in turn causes the computer to hang with a STOP error message.

RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Windows NT 4.0 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

The English-language version of this fix should have the following file attributes or later:


   Date      Time                 Size     File name     Platform
   --------------------------------------------------------------
   09/29/99  07:49 PM             134,416  Sfmsrv.sys    Intel
   09/29/99  07:48 PM             241,744  Sfmsrv.sys    Alpha

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.

Additional query words: halt

Keywords : kbbug4.00 kbfix4.00
Version : winnt:4.0,4.0 SP4,4.0 SP5
Platform : winnt
Issue type : kbbug