Can I access the memory gaps and tail allocated by cudaMallocPitch()?

I found the pitch given by cudaMallocPitch()
is a mutiple of 512 for my M2090 with CUDA 5.0.

Can I access the gap mem between (width, pitch]
and tail mem ((height - 1) * pitch + width, height * pitch] ?

i.e. is the following code safe and allowed?

// init
const char* buf="hello world!";
char* pMem;
size_t pitch;

// alloc dev mem
cudaMallocPitch(&pMem, &pitch, 1, 2);

// write gap
cudaMemcpy(&pMem[1], buf, 12, Host2Device);
// write tail
cudaMemcpy(&pMem[pitch + 1], buf, 12, Host2Device);