Diagnosing and Resolving “Page Fault In Nonpaged Area” BSOD in Windows

By /

Understanding the “Page Fault In Nonpaged Area” Error

Symptoms

The “Page Fault In Nonpaged Area” (IRQL_NOT_LESS_OR_EQUAL) bug check typically manifests as a blue screen of death (BSOD) with the error code 0x00000050. Common symptoms include:

  • System crashes during high memory usage or driver operations
  • Unpredictable reboots or freezes with no clear user action
  • Memory dumps (minidump or full dump) generated in %SystemRoot%\Minidump
  • Event Viewer logs showing critical errors related to kernel-mode drivers or memory access violations

Root Cause

This error occurs when a driver or kernel-mode component attempts to access a memory address that is not mapped into the nonpaged pool. The nonpaged pool is memory that cannot be paged out to disk, reserved for critical kernel objects. Common root causes include:

  • Improper memory allocation or deallocation in kernel drivers (e.g., using nonpaged memory after it has been freed)
  • Hardware issues such as faulty RAM or disk corruption
  • Driver conflicts due to outdated or incompatible kernel-mode modules
  • Malware or corrupted system files interfering with memory management

Diagnosis Tools

Use the following tools to identify the source of the error:

  • BlueScreenView: Analyzes memory dumps to pinpoint the problematic driver or module.
  • Windows Debugger (WinDbg): Parses dump files to inspect stack traces and driver interactions.
  • Event Viewer: Reviews system logs for timestamps and error codes preceding the crash.
  • Memtest86: Tests RAM for defects that might cause memory access errors.
  • Process Monitor: Tracks file system, registry, and process activity for anomalies.

Example Code

The following C++ snippet illustrates a hypothetical driver causing the error by accessing an invalid memory address:


#include <wdf.h>

NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath) {
PDEVICE_OBJECT deviceObject;
NTSTATUS status = IoCreateDevice(DriverObject, 0, NULL, FILE_DEVICE_UNKNOWN, 0, FALSE, &deviceObject);

if (!NT_SUCCESS(status)) {
return status;
}

PVOID nonpagedMemory = ExAllocatePoolWithTag(NonPagedPool, 1024, 'Tag');
if (nonpagedMemory) {
RtlZeroMemory(nonpagedMemory, 1024);
ExFreePool(nonpagedMemory);
// Incorrect access after free: vulnerable to race conditions
RtlZeroMemory(nonpagedMemory, 1024); // This will cause a page fault
}

return STATUS_SUCCESS;
}

Step-by-Step Solution

Step 1: Collect and Analyze Memory Dumps
Open the minidump file in WinDbg and run the command: !analyze -v. Look for the “FAULTING_MODULE” and “STACK_TRACE” to identify the culprit driver.

Step 2: Check for Driver Conflicts
Use devmgmt.msc to review installed drivers. Update or roll back drivers listed in the dump analysis. For example, if usbport.sys is flagged, reinstall USB drivers from the manufacturer.

Step 3: Validate System Hardware
Run Memtest86 to test RAM. Replace faulty hardware if errors are detected. Check chkdsk /f /r for disk corruption.

Step 4: Inspect Kernel-Mode Code
Review the driver’s use of ExAllocatePoolWithTag or MmGetSystemAddressForMdl in the code. Ensure all allocated memory is properly freed before reuse, and validate MDLs with MDL->MdlFlags.

Step 5: Apply OS and Driver Updates
Install the latest Windows updates and driver firmware. Use msinfo32 to check for system-specific compatibility issues.

Step 6: Monitor with Kernel-Mode Tools
Utilize Poolmon and !pool in WinDbg to track nonpaged pool usage. Adjust driver code to avoid overutilizing the nonpaged pool.

Scroll to Top