VirtualQueryEx fails and I'm getting GetLastError 0x18.

this is how i defined MEMORY_BASIC_INFORMATION:

struct MEMORY_BASIC_INFORMATION
BaseAddress dq ?
AllocationBase dq ?
AllocationProtect dd ?
PartitionId dw ?
RegionSize dq ?
State dd ?
Protect dd ?
Type dd ?
ends


https://learn.microsoft.com/en-us/windows/win32/api/winnt/ns-winnt-memory_basic_information


and this is how i opened the handle:

invoke OpenProcess,PROCESS_QUERY_INFORMATION or PROCESS_VM_READ ,FALSE,[ProcId]

I also tried PROCESS_ALL_ACCESS but no luck.


and this is how i call VirtualQueryEx :

invoke VirtualQueryEx,dword [ProcHandle],r13,addr mbi,sizeof.MEMORY_BASIC_INFORMATION

r13 = points to valid memory region which is PAGE_READONLY but I got no idea why VirtualQueryEx fails, any ideas? I'm coding in 64 bit.

In x64 HANDLE is not a DWORD (It is a QWORD).
So, why "dword [ProcHandle]" is used as a handle?

I changed it:
invoke VirtualQueryEx,qword [ProcHandle],r13,addr mbi,sizeof.MEMORY_BASIC_INFORMATION


but still GetLastError 0x18

The culprit was MEMORY_BASIC_INFORMATION, for 64 bit it needs some padding:

struct MEMORY_BASIC_INFORMATION
BaseAddress dq ?
AllocationBase dq ?
AllocationProtect dd ?
PartitionId dw ?
_padding1 dw ?
RegionSize dq ?
State dd ?
Protect dd ?
Type dd ?
_padding2 dd ?
ends

Well done.
I find no such structure in x64 headers for FASM, not in standard download.
Maybe someone should fix that.
I think if you search the forum --- you can find the more full and proper header for x64 coding.

I think I've seen it a while ago, I'll take a look around.

I think if you go to this forum, I mean "Windows" forum --- there is a 'sticky' post there with the files.

i wrote such code that deals with VM and process winapi multiple times, except that i no longer have such code.

it would be much easier to share a minimal example instead of me writing one from scratch.