I am using posix_memalign to allocate memory, but when I try to use the vector I get segmentation failure

Question

I created the following function that takes all the elements of the square matrix to a vector of the appropriate size.The function works correctly with malloc, but I need to create the vector with posix_memalign and there the error occurs.

void convert_matrix_to_vector(int **matrix, const int matrixSize, int **vector, int *vectorSize){

    int *vectorAux, i, j, k, vectorSizeAux;

    vectorSizeAux = matrixSize * matrixSize;
    posix_memalign((void **)&vectorAux, vectorSizeAux, vectorSizeAux * sizeof(int));    
    k = 0;
    for (i = 0; i < matrixSize; i++){
        for (j = 0; j < matrixSize; j++){
            vectorAux[k] = matrix[i][j];
            k++;
        }
    }
    free_matrix_memory(matrix, matrixSize);
    *vector = vectorAux;
    *vectorSize = k;
}

When I run the program, the value of vectorSizeAux is 16.

The error that appears is: Program received signal SIGSEGV, Segmentation fault.

When trying to execute the line:

vectorAux[k] = matrix[i][j];

Answer 1

This answer is thanks to the user "Some programmer dude":

the POSIX reference page states that the alignment must be a power of 2 and also amultiple of sizeof(void*). If you're on a 64-bit system then sizeof(void*) will be 8 which makes 4 an invalid alignment.

That is why the minimum size for vectorSizeAux must be 8, and I got errors when running the program giving it values of 4, 8 and 16. In the value of 4, posix_memalign failed and the execution stopped and I no longer work with the other values.