diff --git a/fs/io_uring.c b/fs/io_uring.c
index 0d491ad15b66..cddc0e8490af 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5066,7 +5066,7 @@ static int io_uring_cmd_prep(struct io_kiocb *req,
 {
 	struct io_uring_cmd *ioucmd = &req->uring_cmd;
 
-	if (sqe->rw_flags)
+	if (sqe->rw_flags || sqe->__pad1)
 		return -EINVAL;
 	ioucmd->cmd = sqe->cmd;
 	ioucmd->cmd_op = READ_ONCE(sqe->cmd_op);
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index f10b59d6693e..0ad3da28d2fc 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -22,7 +22,10 @@ struct io_uring_sqe {
 	union {
 		__u64	off;	/* offset into file */
 		__u64	addr2;
-		__u32	cmd_op;
+		struct {
+			__u32	cmd_op;
+			__u32	__pad1;
+		};
 	};
 	union {
 		__u64	addr;	/* pointer to buffer or iovecs */