How safe is Marshal class?

Hello...

How safe is this piece of code?

//allocate 10 bytes

IntPtr p = Marshal.AllocHGlobal(10);

byte[] a = new byte[20];

for (byte i = 0; i < a.Length; ++i) a[i] = i;

//copy the buffer

Marshal.Copy(a, 0, p, a.Length);

Here's some pictures that shows the memory before and ...

after the copying...