January 6, 2006 - I am passing along this issue of MICROSOFT HARDWARE NEWS
because it mentions two new NDIS-related Microsoft KB Articles.

Regards,

Thomas F. Divine



*********************************************************************
MICROSOFT HARDWARE NEWS

*********************************************************************

January 6, 2004


IN THIS ISSUE...

. News for Driver Developers
- Thread Scheduling, Thread Context, and Processor IRQLs
- Help Improve WHDC Online and News Activities
. Windows Driver Security Tips
. Microsoft KB Articles
. About This Newsletter


*****************************************************
News for Driver Developers
*****************************************************

**What Every Windows Kernel-mode Driver Writer Needs to Know
About Thread Scheduling, Thread Context, and Processor IRQLs**

Thread scheduling, thread context, and the current interrupt request level
(IRQL) for each processor have important effects on how drivers work.

An IRQL defines the hardware priority at which a processor operates at any
given time. In the Windows Driver Model, a thread running at a low IRQL can
be interrupted to run code at a higher IRQL.

A thread's scheduling priority and the processor's current IRQL determine
whether a running thread can be pre-empted or interrupted. In thread
pre-emption, the MicrosoftR WindowsR family of operating systems replaces
the running thread with another thread, usually of higher thread priority,
on the same processor. The effect of pre-emption on an individual thread is
to make the processor unavailable for a while. In thread interruption, the
operating system forces the current thread to temporarily run code at a
higher interrupt level.

Interruption and pre-emption both affect how code that runs in the thread
can access data structures, use locks, and interact with other threads. When
writing kernel-mode drivers, an understanding of the relationship between
threads and IRQLs in Windows will lessen the common hangs and crashes
generated by mishandled hardware interrupts.

The white paper "Scheduling, Thread Context, and IRQL" presents information
about how thread scheduling, thread context, and a processor's current IRQL
affect the operation of kernel-mode drivers for the Microsoft Windows family
of operating systems. This white paper includes explanations of
processor-specific and thread-specific IRQLs that are commonly used by
drivers, detailed examples of thread pre-emption or interruption on single
and multiprocessor systems, and a chart that contains a list of the standard
driver routines together with the IRQL at which each routine is called and
the thread context in which the routine runs, plus techniques and best
practices driver writers can use to troubleshoot their code.

>>Call to Action

. To avoid common IRQL-related problems, driver writers should
be familiar with:
> The thread scheduling mechanism of the operating system
> The thread context in which driver routines can be called
> The appropriate use of driver-dedicated and system worker
threads
> The significance of various IRQLs and what driver code can
and cannot do at each IRQL

. Download and read the "Scheduling, Thread Context, and IRQL"
white paper at:
http://www.microsoft.com/whdc/hwdev/driver/IRQL.mspx

. Follow the best practices outlined in the "Scheduling, Thread
Context,and IRQL" white paper.


Resources...

. The Microsoft Windows Driver Development Kit (DDK)
http://www.microsoft.com/whdc/ddk/winddk.mspx

. A companion paper, "Locks, Deadlocks, and Synchronization,"
which addresses synchronization issues in drivers, will be
available from WHDC later in January 2004.



**Help Improve WHDC Online and News Activities**

The WHDC team is conducting an online survey during December to help us
understand how we can improve the WHDC online and news activities in ways
that will make it easier for you to do your job. Please take this
opportunity to tell us what we can do better.

>>Call to Action:

. Complete the survey now by going to:
http://www.microsoft.com/whdc/hwdev/hardware/survey.mspx



*****************************************************
Windows Driver Security Tips
*****************************************************

**Know the Limits of Your Code and Press the Limits of Bad Data**

Inadequate documentation of your code's features makes diagnosing potential
security problems much more difficult in the future. Knowing the source
files that are used, the temporary files that are written, and the data file
types that your driver allows a user to open or save will give you clues to
which files could be changed or manipulated by a malicious user.

For example, analyzing the buffer sizes for a data field by using your
driver's documentation can make it easier for you to design tests that check
for buffer overruns. It's always better that you check the buffer sizes in
your code before a hacker does.

>>Call to Action

. Document the basic features of your driver code.
. Simulate the actions of a malicious user on your code.

Testing your driver code for buffer overruns can be as simple as trying to
force an input string of 256 characters into a field that is documented as
255 characters long.

Resources...

. WHDC Drivers and Security Web site:
http://www.microsoft.com/whdc/hwdev/driver/security/default.mspx



*****************************************************
Microsoft KB Articles
*****************************************************

Change in how self-directed loopback packets are processed
for Windows XP: http://support.microsoft.com/default.aspx?id=813542

Known issues with intermediate (IM) driver samples in
Windows 2000 and Windows XP DDKs:
http://support.microsoft.com/default.aspx?id=323458

The 1394 host controller properties dialog box incorrectly shows the Power
Management tab: http://support.microsoft.com/default.aspx?id=328902



*****************************************************
About This Newsletter
*****************************************************

The Microsoft Hardware Newsletter, a publication of Microsoft Windows
Hardware and Driver Central, is a monthly resource for developers who are
creating new hardware and drivers for Microsoft Windows operating systems.

Did you get this newsletter from a friend? To subscribe to the Microsoft
Hardware Newsletter, visit:
http://register.microsoft.com/regsys/decisionpoint.asp






Microsoft Communities is your launching pad for communicating online with
peers and experts about Microsoft products, technologies, and services:
http://communities.microsoft.com/home/default.asp

~~~~~~~~~~~~~~~~~~~~~~~~~ How to use this mailing
list~~~~~~~~~~~~~~~~~~~~~~~~

To cancel your subscription to this newsletter, either click
mailto:1_56644_4E56471E-6F0C-D111-9D3E-0000F84121EB_US@...
.com?subject=UNSUBSCRIBE to send an unsubscribe e-mail or reply to this
message with the word UNSUBSCRIBE in the Subject line. You can also
unsubscribe at http://www.microsoft.com/misc/unsubscribe.htm. You can manage
all your Microsoft.com communication preferences from this site.

THIS DOCUMENT AND OTHER DOCUMENTS PROVIDED PURSUANT TO THIS PROGRAM ARE FOR
INFORMATIONAL PURPOSES ONLY. The information type should not be interpreted
to be a commitment on the part of Microsoft and Microsoft cannot guarantee
the accuracy of any information presented after the date of publication.
INFORMATION PROVIDED IN THIS DOCUMENT IS PROVIDED 'AS IS' WITHOUT WARRANTY
OF ANY KIND. The user assumes the entire risk as to the accuracy and the use
of this document.
microsoft.com newsletter e-mail may be copied and distributed subject to the
following conditions: 1. All text must be copied without modification and
all pages must be included 2. All copies must contain Microsoft's copyright
notice and any other notices provided therein 3. This document may not be
distributed for profit