C言語;ハッシュ;add関数の動作停止

前提

C言語でハッシュを用いた、プログラムを作っています。

発生している問題

コンパイラは通りますが、実行中に動作が停止します。
空のハッシュテーブルに連結リストを入れるときは、動作は停止しませんが。
連結リストが存在するハッシュテーブルに連結リストを入れようとすると、動作が停止します。
何が問題で、どうやって解決すればよろしいでしょうか？

該当のソースコード

Ｃ言語

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

#define HASHSIZE 17
struct match *hashtable[HASHSIZE];

struct match_score{
  int year;
  int month;
  int day;
  int home_score;
  int away_score;
  struct match_score *next;
} ;

struct match{
  char *home;
  char *away;
  struct match_score *r;
  struct match *next;
} ;

int hash(char *home, char *away);                                                                                             
struct match *make_match(char *home, char *away, struct match_score *r, struct match *next);                                  
struct match_score *make_match_score(int year, int month, int day, int home_score, int away_score, struct match_score *next); 
void add(int year, int month, int day, char *home, int home_score, int away_score, char *away);                              
struct match *find(char *home, char *away);                                                                                   

int main(void) {

  for(int i=0; i < HASHSIZE; i++){
    hashtable[i] = NULL;
  }

  printf("%d\n",hash("Kashima_Antler", "Yokohama_Flugels"));
  add(1992, 9, 5, "Kashima_Antler", 4, 2, "Yokohama_Flugels");
  printf("%d\n",hashtable[2]->r->year);
  add(1996, 5, 12, "mashima_Antler", 3, 1, "Yokohama_Flugels");
  printf("%d\n",hashtable[2]->r->year);

  return 0;
}

int hash(char *home, char *away) {
  int hashval = 0;
  int i = 0;

  while(home[i] != '\0') {
    hashval += home[i];
    i++;
  }
  while(away[i] != '\0') {
    hashval += away[i];
    i++;
  }

  return hashval % HASHSIZE;
}

struct match_score *make_match_score(int year, int month, int day, int home_score, int away_score, struct match_score *next) {
  struct match_score *newmsp = malloc(sizeof(struct match));
  if (newmsp != NULL) {
    newmsp->year = year;
    newmsp->month = month;
    newmsp->day = day;
    newmsp->home_score = home_score;
    newmsp->away_score = away_score;
    newmsp->next = next;
  }
  return newmsp;
}

struct match *make_match(char *home, char *away, struct match_score *r, struct match *next) {
  struct match *newmp = malloc(sizeof(struct match));
  if (newmp != NULL) {
    newmp->home = (char*)malloc(sizeof(char) * sizeof(home));
    newmp->away = (char*)malloc(sizeof(char) * sizeof(away));
    strcpy(newmp->home, home);
    strcpy(newmp->away, away);
    newmp->r = r;
    newmp->next = next;
  }
  return newmp;
}

struct match *find(char *home, char *away) {
  struct match *p;
  int hashval = hash(home, away);
  p = hashtable[hashval];
  while (p != NULL) {
    if (strcmp(home, p->home) == 0 && strcmp(away, p->away) == 0) {
      return p;                                                                                          
    }
    p = p->next;
  }
  return NULL;
}

void add(int year, int month, int day, char *home, int home_score, int away_score, char *away) {
  struct match *newmp = NULL;
  struct match_score *newmsp = NULL;
  int hashval = hash(home,away);
  struct match *pmatch = NULL;
  struct match *prematch = NULL;

  if (hashtable[hashval] == NULL) {
    newmsp = make_match_score(year, month, day, home_score, away_score, NULL);
    newmp = make_match(home, away, newmsp, hashtable[hashval]);
    hashtable[hashval] = newmp;
    return ;
  }

  struct match *fmp = find(home, away);

  if (fmp != NULL) {
    newmsp = make_match_score(year, month, day, home_score, away_score, fmp->r);
    fmp->r = newmsp;
    return ;
  }

  newmsp = make_match_score(year, month, day, home_score, away_score, NULL);
  newmp = make_match(home, away, newmsp, hashtable[hashval]);
  hashtable[hashval] = newmp;

  return ;
}