It is understandable that for 64 bit, virtualAlloc function we have used address spaces greater than 32 bit to avoid truncation bug. However, we could pick any random address space greater than 32 bit, instead of bruteforcing. In case, the address space is already reserved and committed, the address will be rounded down to next page boundary. In this regard please refer to Microsoft documentation.
https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-virtualalloc
It is understandable that for 64 bit, virtualAlloc function we have used address spaces greater than 32 bit to avoid truncation bug. However, we could pick any random address space greater than 32 bit, instead of bruteforcing. In case, the address space is already reserved and committed, the address will be rounded down to next page boundary. In this regard please refer to Microsoft documentation.
https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-virtualalloc