Defrag Tools: #16 - WinDbg - Driver Verifier

Not all Blue Screens of Death are easy to debug! Sometimes, you need to enable extra checking to help catch a buggy device driver. In this episode of Defrag Tools, Chad Beeder and Larry Larsen discuss using Driver Verifier in conjunction with WinDbg to track down a driver which is corrupting kernel mode pool memory.

Debugger commands used:

• !analyze -v
• .trap
• ub
• dp
• dps
• dc
• kv

Make sure you watch Defrag Tools Episode #1 for instructions on how to get the Debugging Tools for Windows and how to set the required environment variables for symbols and source code resolution.

Resources:

Debugging Tools for Windows

Windows Internals book tools (including NotMyFault)

Forcing a System Crash from the Keyboard

How to generate a complete crash dump file or a kernel crash dump file by using an NMI on a Windows-based system

Driver Verifier Options

Timeline:

[00:09] - What is Driver Verifier?
[01:54] - Using NotMyFault to cause a buffer overflow
[06:04] - Looking at a buffer overflow dump in WinDbg
[08:10] - What is the .trap command? (see: x64 Register Usage)
[12:45] - First dump was inconclusive. Looking at a second buffer overflow dump.
[15:47] - Memory is corrupted, but how to find out who is corrupting it? Driver Verifier!
[16:55] - Launching and configuring Driver Verifier
[20:20] - Verifier enabled, let's crash the system!
[21:25] - What is special pool?
[22:27] - Looking at the memory dump (captured with Verifier enabled)
[25:13] - Forcing a memory dump of a hung system via keyboard
[28:00] - Forcing a memory dump of a hung system via NMI switch
[31:52] - Advanced/custom Driver Verifier settings