C中的棘手段错误

我正在尝试为我的大学任务运行一个C项目,并且我在以下代码段中的“while(current-> next！= NULL){”行中遇到了一个seg错误：

FILE* f = fiLeopen("test.txt");
if (f != NULL){
    functionList = fileReadToMemory(f,&graPHParams);//functionList is a pointer to the first value of the linked list it creates
    current = functionList;

    while (current->next != NULL) {
        printf("%d %d %d %s",current->red,current->green,current->blue,current->expression);//Prints value of linked list
        current = current -> next;
    }
}

gdb给我的错误如下：

Program received signal EXC_BAD_ACCESS,Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x000000000000003a
0x0000000100000b30 in main () at main.c:23
23          while (current->next != NULL) {

我究竟做错了什么？

提前致谢！

while (current != NULL)

current->next != NULL