Thursday 18 July 2013

Debugging a Stop 0x9F Even Further - Using !drvobj

We're back with another Stop 0x9F to debug, in my opinion, these bugchecks are usually the easiest bugchecks to debug, since they usually point out the driver with the !irp extension, but sometimes the !irp extension may not reveal the true cause.

The two parameters we're interested in are, parameter 2 and parameter 4. The second parameter specifies the physical device which the associated problematic driver belongs to, and the fourth parameter specifies the IRP which seems to be blocking any further progress.

If we can examine the IRP, we can from the stack, that the driver which seems to be causing the problem is a Microsoft USB Hub driver, but from my experience, Microsoft driver are rarely the true cause for the crash.

So, let's debug deeper into the dump file (Minidump), and see which drivers are associated with the device. We can the !drvobj extension to view the associated drivers which control the device.

We can now see all the associated Dispatch routines for that device, and the drivers which issue these routines, we can at the bottom a third-party driver which is related to theVMware USB Monitor driver, which seems to be potentially outdated. The driver's associated dispatch routine is IRP_MJ_PNP, this major function code is used to request when PnP activity should occur.

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