MPI_scatter: Invalid buffer pointer

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C++

parallel

can anybody tell what am I doing wrong due to which I am getting this error.The error that I am getting is Fatal Error: fatal error in MPI_Scatter: Invalid buffer pointer, error stack:MPI_Scatter(760):MPI_Scatter(sbuf=0x0085f7ac , scount , MPI_INT , rbuf =0x0000000 , rcount =1, MPI_INT , root= 0 , MPI_COMM_WORLD) failed

#include<stdio.h>
#include<mpi.h>

void transpose(int ** p, int row, int col)
{
    int ** tempVar;
    tempVar = (int *)malloc(sizeof(int *)* row);
    int i = 0;
    for (; i < row; i++)
    {
        tempVar[i] = (int *)malloc(sizeof (int *)* col);
        int j = 0;
        while (j < col)
        {
            tempVar[i][j] = p[j][i];
            j++;
        }
    }
    p = tempVar;
}
void main(int argc, char * argv[])
{
    int rank, size;
    MPI_Init(argc, argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    int d[] = { 1000, 1000, 1000, 1000, 1000, 1000 };
    int vt[6] = { 1000, 1000, 1000, 1000, 1000, 1000 };
    int ** p;
    p = (int *)malloc(sizeof(int *)* 6);
    int i = 0;
    int row = 6;
    int col = 6;
    while (i < 6)
    {
        p[i] = (int *)malloc(sizeof(int *)* 6);
        /*int j = 0;
        if (rank == 0)
        {
            while (j < 6)
            {
                scanf("%d", p[i][j]);
                j++;
            }
        }*/
        i++;    
    }
    p[0][0] = 0; p[0][1] =2 ; p[0][2] =3 ; p[0][3] =1 ; p[0][4] =1000 ; p[0][5] =1000 ;
    p[1][0] = 2; p[1][1] = 0; p[1][2] = 1000; p[1][3] = 1000; p[1][4] = 5; p[1][5] = 1000;
    p[2][0] = 3; p[2][1] = 1000; p[2][2] = 0; p[2][3] = 1000; p[2][4] = 1000; p[2][5] = 1;

    p[3][0] = 1; p[3][1] = 1000; p[3][2] = 1000; p[3][3] = 0; p[3][4] = 4; p[3][5] = 3;

    p[4][0] = 1000; p[4][1] = 5; p[4][2] = 1000; p[4][3] = 4; p[4][4] = 0; p[4][5] = 2;

    p[5][0] = 1000; p[5][1] = 1000; p[5][2] = 1; p[5][3] = 3; p[5][4] = 2; p[5][5] = 0;
    int smallest;   
    if (rank == 0)
    {
        //transpose(&p , row , col);
        smallest = 0;
        vt[smallest] = smallest;
        //MPI_Bcast();
    }
    int  vt1, d1;
    vt1 = d1 = 0;

    int roww[6];
    MPI_Scatter(vt, 6, MPI_INT, vt1, 1, MPI_INT, 0, MPI_COMM_WORLD);
    MPI_Scatter(d, 6, MPI_INT, d1, 1, MPI_INT, 0, MPI_COMM_WORLD);
    MPI_Scatter(p, row *row, MPI_INT,roww, 6, MPI_INT, 0, MPI_COMM_WORLD);
    i = 0;
    while (i < (row*row)/size)
    {
        MPI_Bcast(smallest, 1, MPI_INT, 0, MPI_COMM_WORLD);
        if (vt1 != rank)
        {
            if (roww[smallest] != 1000)
            {   
                if (d1 > roww[smallest])
                    d1 = roww[smallest];
            }
        }

        MPI_Gather(d1, 1, MPI_INT, d, row, MPI_INT, 0, MPI_COMM_WORLD);
        if (rank == 0)
        {
            smallest = d[0];
            int k = 1;
            int index = 0;
            while (k < 6)
            {
                if (d[k] < smallest)
                {
                    smallest = d[k];
                    index = k;
                }
                k++;
            }
            vt[k] = index;

        }
        MPI_Scatter(vt, 6, MPI_INT, vt1, (row) / size, MPI_INT, 0, MPI_COMM_WORLD);
        MPI_Scatter(d, 6, MPI_INT, d1, (row) / size, MPI_INT, 0, MPI_COMM_WORLD);

    }
    MPI_Finalize();
}