Passing pointer between DLL boundary question

Hi

This may be a stupid question, but I want to make sure my understanding
is correct. I understand that allocating a memory inside a DLL and
freeing the memory in the program that uses the DLL (or vice versa) is
not a good idea, but if a pointer passed between a DLL boundary is
allocated and freed at the correct place, is the code guaranteed to be
safe? For example:

1. In dll implementation code:

static const char someString[] = "a string";

void GetString(const char** ps)
{
     if(ps)
         *ps = &(someString[0]);
}

And in application code:

const char* aString;
GetString(&aString);
cout << aString;

2. Another example: in dll implementation code:

static void* data = 0;
static int dataSize = 0;

///... functions that manipulate data

int GetData(void* buff, int buffSize)
{
    if(buff && buffSize >= dataSize)
    {
        memcpy(buff, data, dataSize);
        return dataSize;
    }
    return 0;
}
(buff is a buffer allocated and freed in the application).

I tried on my VC++ 6, both examples run fine, but are they always
guaranteed to be safe? Are there any side effects that I should be
aware of? Thanks!