diff --git a/pintos-env/pintos/threads/thread.c b/pintos-env/pintos/threads/thread.c
index 361a083..7305c7b 100644
--- a/pintos-env/pintos/threads/thread.c
+++ b/pintos-env/pintos/threads/thread.c
@@ -427,6 +427,7 @@ thread_exit (void)
 {
   ASSERT (!intr_context ());
 
+
 #ifdef USERPROG
   process_exit ();
 #endif
@@ -436,7 +437,7 @@ thread_exit (void)
      when it calls thread_schedule_tail(). */
   intr_disable ();
   struct thread* t = thread_current();
-  //printf("Exit status: %d\n",t->exit_status);
+  printf("%s: exit(%d)\n", t->name, t->exit_status);
   list_remove (&t->allelem);
   sema_up(&t->waiting_sem);
   sema_down(&t->parent->parent_sem);
@@ -589,6 +590,7 @@ init_thread (struct thread *t, const char *name, int priority)
   sema_init(&t->waiting_sem, 0);
   sema_init(&t->parent_sem, 0);
   t->waited_on_before = 0;
+  t->exit_status = -1;
   list_init(&t->children);
 
   if (thread_mlfqs) {
diff --git a/pintos-env/pintos/userprog/syscall.c b/pintos-env/pintos/userprog/syscall.c
index 9eabd30..665bf8b 100755
--- a/pintos-env/pintos/userprog/syscall.c
+++ b/pintos-env/pintos/userprog/syscall.c
@@ -218,7 +218,10 @@ int sys_read(int fd, void *buffer, unsigned size) {
 }
 
 int sys_write(int fd, const void *buffer, unsigned size) {
-  if (check_ptr(buffer)||check_ptr(buffer+size)) return -1;
+  unsigned i;
+  for (i = 0; i <= size; i++) {
+    if (check_ptr(buffer + size)) return -1;
+  }
   int ret;
 
   if(fd == 1) { // write to stdout
@@ -266,7 +269,6 @@ int
 sys_exit (int status)
 {
   struct thread* t = thread_current();
-  printf("%s: exit(%d)\n", t->name, status);
   t->exit_status = status;
   thread_exit();
   return -1;