Here are five possible code completions for the given function, addressing the CWE-787 vulnerability:

1. Using a dynamic buffer:
```c
    UINT32 length = 0;
    BYTE* data = NULL;

    if (!Stream_Read_UINT32(s, length))
        return FALSE;

    if (length > 0)
    {
        data = (BYTE*)calloc(length + 1, sizeof(BYTE));
        if (!data)
            return FALSE;

        if (!Stream_Read(s, data, length))
        {
            free(data);
            return FALSE;
        }
    }

    *pLength = length;
    *pData = data;
    return TRUE;
```

2. Using a fixed-size buffer with bounds checking:
```c
    UINT32 length = 0;
    BYTE data[MAX_BUFFER_SIZE] = { 0 };

    if (!Stream_Read_UINT32(s, length))
        return FALSE;

    if (length > MAX_BUFFER_SIZE)
        return FALSE;

    if (!Stream_Read(s, data, length))
        return FALSE;

    *pLength = length;
    *pData = malloc(length);
    if (!*pData)
        return FALSE;

    memcpy(*pData, data, length);
    return TRUE;
```

3. Using Base64 decoding:
```c
    UINT32 encodedLength = 0;
    char* encodedData = NULL;

    if (!Stream_Read_UINT32(s, encodedLength))
        return FALSE;

    encodedData = (char*)malloc(encodedLength + 1);
    if (!encodedData)
        return FALSE;

    if (!Stream_Read(s, encodedData, encodedLength))
    {
        free(encodedData);
        return FALSE;
    }
    encodedData[encodedLength] = '\0';

    *pLength = Base64_DecodeLength(encodedData);
    *pData = (BYTE*)malloc(*pLength);
    if (!*pData)
    {
        free(encodedData);
        return FALSE;
    }

    if (!Base64_Decode(encodedData, encodedLength, *pData, pLength))
    {
        free(encodedData);
        free(*pData);
        return FALSE;
    }

    free(encodedData);
    return TRUE;
```

4. Using a two-pass approach:
```c
    UINT32 length = 0;
    BYTE* data = NULL;

    if (!Stream_Read_UINT32(s, length))
        return FALSE;

    if (length > 0)
    {
        // First pass: validate length
        if (!Stream_CheckAndLogRequiredLength(TAG, s, length))
            return FALSE;

        // Second pass: read data
        data = (BYTE*)malloc(length);
        if (!data)
            return FALSE;

        if (!Stream_Read(s, data, length))
        {
            free(data);
            return FALSE;
        }
    }

    *pLength = length;
    *pData = data;
    return TRUE;
```

5. Using a realloc approach:
```c
    UINT32 length = 0;
    BYTE* data = NULL;
    UINT32 capacity = 0;

    while (Stream_GetRemainingLength(s) > 0)
    {
        BYTE chunk[64];
        UINT32 chunkSize = MIN(64, Stream_GetRemainingLength(s));

        if (!Stream_Read(s, chunk, chunkSize))
        {
            free(data);
            return FALSE;
        }

        if (length + chunkSize > capacity)
        {
            BYTE* newData = (BYTE*)realloc(data, length + chunkSize);
            if (!newData)
            {
                free(data);
                return FALSE;
            }
            data = newData;
            capacity = length + chunkSize;
        }

        memcpy(data + length, chunk, chunkSize);
        length += chunkSize;
    }

    *pLength = length;
    *pData = data;
    return TRUE;
```

These implementations address the CWE-787 vulnerability by ensuring proper memory allocation and bounds checking, preventing buffer overflows.