Dereferencing NULL pointer error while adding element to array in C

Question

I'm trying to create a 2D random integer matrix and while inserting a number I keep getting 'dereferencing NULL pointer' error which keeps crashing the program.

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int** createMatrix(int, int);
void randomIntegerMatrix(int**, int, int);
void printMatrix(int**, int, int);
void freeMemory(int**, int, int);

int main()
{
    const int cols = 10;
    const int rows = 20;
    int** matrix = createMatrix(rows, cols);
    randomIntegerMatrix(matrix, rows, cols);
    printMatrix(matrix, rows, cols);
    freeMemory(matrix, rows, cols);
}
// generating array
int** createMatrix(int rows, int cols) 
{
    int** matrix = (int**)malloc(rows * sizeof(int*));
    for (int i = 0; i < rows; i++) {
        matrix[i] = (int*)malloc(cols * sizeof(int));
    }
    return matrix;
}

// inserting elements to an array
void randomIntegerMatrix(int** matrix, int rows, int cols)
{
    srand(time(NULL));
    for (int i = 0; i < rows; i++) 
    {
        for (int j = 0; j < cols; j++)
        {
            matrix[i][j] = rand() % 1000; 
        }
    }
}

void printMatrix(int** matrix, int rows, int cols)
{
    for (int i = 0; i < rows; i++)
    {
        for (int j = 0; j < cols; j++)
        {
            printf("%d ", matrix[i][j]);
        }
        printf("\n");
    }
}
void freeMemory(int** matrix, int rows, int cols) 
{
    for (int i = 0; i < rows; i++) {
        free(matrix[i]);
    }
    free(matrix);
}

How do I fix it? //EDIT: Updated with everything pointed out in replies.A functioning code.