[HUST CSE IoTS&P Lab] [fix] check rt_mutex_create return value (#7169)

components/lwp/lwp_syscall.c

@@ -1016,6 +1016,8 @@ rt_err_t sys_sem_release(rt_sem_t sem)
 rt_mutex_t sys_mutex_create(const char *name, rt_uint8_t flag)
 {
     rt_mutex_t mutex = rt_mutex_create(name, flag);
+    if(mutex == NULL)
+        return NULL;
     if (lwp_user_object_add(lwp_self(), (rt_object_t)mutex) != 0)
     {
         rt_mutex_delete(mutex);