io_uring/fs: check unused sqe fields for unlinkat

Zero check unused SQE fields addr3 and pad2 for unlinkat. They're
not needed now, but could be used sometime in the future.

Signed-off-by: Yi Xie <xieyi@kylinos.cn>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://patch.msgid.link/20260714030306.64820-1-xieyi@kylinos.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Yi Xie

io_uring/fs.c

@@ -110,7 +110,8 @@ int io_unlinkat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	const char __user *fname;
 	int err;
 
-	if (sqe->off || sqe->len || sqe->buf_index || sqe->splice_fd_in)
+	if (sqe->off || sqe->len || sqe->buf_index || sqe->splice_fd_in ||
+	    sqe->addr3 || sqe->__pad2[0])
 		return -EINVAL;
 	if (unlikely(req->flags & REQ_F_FIXED_FILE))
 		return -EBADF;