NtQueryVirtualMemory function (ntifs.h)

The NtQueryVirtualMemory routine determines the state, protection, and type of a region of pages within the virtual address space of the specified process.


__kernel_entry NTSYSCALLAPI NTSTATUS NtQueryVirtualMemory(
  [in]            HANDLE                   ProcessHandle,
  [in, optional]  PVOID                    BaseAddress,
  [in]            MEMORY_INFORMATION_CLASS MemoryInformationClass,
  [out]           PVOID                    MemoryInformation,
  [in]            SIZE_T                   MemoryInformationLength,
  [out, optional] PSIZE_T                  ReturnLength


[in] ProcessHandle

Handle for the process in whose context the pages to be queried reside. Use the NtCurrentProcess macro to specify the current process.

[in, optional] BaseAddress

The base address of the region of pages to be queried. This value is rounded down to the next host-page-address boundary.

[in] MemoryInformationClass

The memory information class about which to retrieve information. Currently, the only supported MEMORY_INFORMATION_CLASS value is MemoryBasicInformation.

[out] MemoryInformation

Pointer to a buffer that receives the specified information. The format and content of the buffer depend on the information class specified in the MemoryInformationClass parameter. When the value MemoryBasicInformation is passed to MemoryInformationClass, the MemoryInformation parameter value is a MEMORY_BASIC_INFORMATION structure.

[in] MemoryInformationLength

Specifies the length, in bytes, of the buffer that MemoryInformation points to.

[out, optional] ReturnLength

An optional pointer which, if specified, receives the number of bytes placed in the MemoryInformation buffer.

Return value

Returns STATUS_SUCCESS if the call is successful. If the call fails, possible error codes include the following:

Return code Description
STATUS_ACCESS_DENIED The caller had insufficient access rights to perform the requested action.
STATUS_ACCESS_VIOLATION The specified base address is an invalid virtual address.
STATUS_INFO_LENGTH_MISMATCH The MemoryInformation buffer is larger than MemoryInformationLength.
STATUS_INVALID_INFO_CLASS The specified MemoryInformationClass parameter is invalid.
STATUS_INVALID_PARAMETER The specified base address is outside the range of accessible addresses.


ZwQueryVirtualMemory determines the state of the first page within the region and then scans subsequent entries in the process address map from the base address upward until either the entire range of pages has been scanned or until a page with a non-matching set of attributes is encountered. The region attributes, the length of the region of pages with matching attributes, and an appropriate status value are returned.

If the entire region of pages does not have a matching set of attributes, then the sub-regions within one address reservation will be returned individually. They will have the same *MemoryInformation.AllocationBase value, their individual sizes will be in *MemoryInformation.RegionSize, and the total size of the address reservation can be obtained by summing all of the *MemoryInformation.RegionSize values associated with a particular *MemoryInformation.AllocationBase value.

NtQueryVirtualMemory and ZwQueryVirtualMemory are two versions of the same Windows Native System Services routine.

For calls from kernel-mode drivers, the NtXxx and ZwXxx versions of a Windows Native System Services routine can behave differently in the way that they handle and interpret input parameters. For more information about the relationship between the NtXxx and ZwXxx versions of a routine, see Using Nt and Zw Versions of the Native System Services Routines.


Minimum supported client Windows 2000
Target Platform Universal
Header ntifs.h
Library NtosKrnl.lib
DLL NtosKrnl.exe

See also