ksmbd: fix a missing return value check bug

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix a missing return value check bug In the smb2_send_interim_resp(), if ksmbd_alloc_work_struct() fails to allocate a node, it returns a NULL pointer to the in_work pointer. This can lead to an illegal memory write of in_work->response_buf when allocate_interim_rsp_buf() attempts to perform a kzalloc() on it. To address this issue, incorporating a check for the return value of ksmbd_alloc_work_struct() ensures that the function returns immediately upon allocation failure, thereby preventing the aforementioned illegal memory access.