Execute PE from memory - c

Question

I tried to write LoadLibrary function in C.
The function gets a path to a DLL file which, normally, pops up message box when it loads (I tried to run that DLL file using the original LoadLibrary function and it works).
Basically, the DLL content is loaded into a buffer, parsed and runs from entry point.
In VirtualAllocEx function, I use PAGE_READWRITE protection mode. Then, when running the line f(nth->OptionalHeader.ImageBase, DLL_PROCESS_ATTACH, NULL), I get the following error message: Exception thrown at 0x10011032 in PE.exe: 0xC0000005: Access violation executing location 0x10011032. (0x10011032 is entry point address).
If I change the mode to PAGE_EXECUTE_READWRITE, the error message is: Exception thrown at 0x00019644 in PE.exe: 0xC0000005: Access violation executing location 0x00019644. (No idea what is that address).
I think that it's clear why it's not smart to allow execution in all sectors of the PE, but I did it for testing purposes only. In the final code, I'll need to write it properly.
My code is attached.
(BTW, if you have other suggestions that are not related to my question - I'll glad to know).
#include <Windows.h>
typedef HMODULE func(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved);
HMODULE LoadLibraryFromMem(char* dllPath)
{
DWORD read;
HANDLE handle;
handle = CreateFileA(dllPath, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
DWORD size = GetFileSize(handle, NULL);
PVOID vDll = VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);
BOOL r = ReadFile(handle, vDll, size, &read, NULL);
CloseHandle(handle);
PIMAGE_DOS_HEADER dosh = (PIMAGE_DOS_HEADER)vDll;
PIMAGE_NT_HEADERS nth = (PIMAGE_NT_HEADERS)((PBYTE)vDll + dosh->e_lfanew);
handle = GetCurrentProcess();
PVOID vImg = VirtualAllocEx(
handle,
nth->OptionalHeader.ImageBase,
nth->OptionalHeader.SizeOfImage,
MEM_RESERVE | MEM_COMMIT,
PAGE_READWRITE
); // HERE --> PAGE_EXECUTE_READWRITE
WriteProcessMemory(
handle,
vImg,
vDll,
nth->OptionalHeader.SizeOfHeaders,
0
);
PIMAGE_SECTION_HEADER sech = IMAGE_FIRST_SECTION(nth);
for (size_t i = 0; i < nth->FileHeader.NumberOfSections; i++)
WriteProcessMemory(
handle,
(PBYTE)vImg + sech[i].VirtualAddress,
(PBYTE)vDll + sech[i].PointerToRawData,
sech[i].SizeOfRawData,
0
);
PIMAGE_IMPORT_DESCRIPTOR impd = nth->OptionalHeader.ImageBase + nth->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress;
HANDLE proc;
while (((PIMAGE_IMPORT_DESCRIPTOR)impd)->Name)
{
LPSTR dllName = (nth->OptionalHeader.ImageBase + ((PIMAGE_IMPORT_DESCRIPTOR)impd)->Name);
HMODULE dllAdr = LoadLibraryA(dllName);
PDWORD iat = nth->OptionalHeader.ImageBase + ((PIMAGE_IMPORT_DESCRIPTOR)impd)->FirstThunk;
while (*iat)
{
LPSTR funcName = ((PIMAGE_IMPORT_BY_NAME)(nth->OptionalHeader.ImageBase + *iat))->Name;
proc = GetProcAddress(dllAdr, funcName);
if (!proc)
return NULL;
impd->FirstThunk = proc;
iat++;
}
impd++;
}
func* f = (func*)(nth->OptionalHeader.ImageBase + nth->OptionalHeader.AddressOfEntryPoint);
f(nth->OptionalHeader.ImageBase, DLL_PROCESS_ATTACH, NULL);
}
int main()
{
LoadLibraryFromMem("mydll.dll");
return 0;
}
Thanks in advance!