C qsort() using struct

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

struct mytype
{
    struct mytype *next;
    int key;
};

struct mytype *mysort;


int cmpfunc (const void * a, const void * b)
{
    struct mytype* aa = (struct mytype*)a; 
    struct mytype* bb = (struct mytype*)b; 
   
    return (aa->key - bb->key);
}

int main()
{
    mysort = (struct mytype*)malloc(sizeof(struct mytype*)*10);
    int i;
    for( i = 0; i < 10; i++)
    {   
        mysort[i].key = 10-i;
    }   
   printf("before sorting\n");

    for( i = 0; i < 10; i++)
        printf("%d ", mysort[i].key);
    printf("\n");

    qsort(mysort, 10, sizeof(struct mytype), cmpfunc);

    printf("after sorting\n");
    for( i = 0; i < 10; i++)
        printf("%d ", mysort[i].key);
    printf("\n");


    return 0;
}