io_uring: nospec index for tags on files update

Don't forget to array_index_nospec() for indexes before updating rsrc
tags in __io_sqe_files_update(), just use already safe and precalculated
index @i.

Fixes: c3bdad02 ("io_uring: add generic rsrc update with tags")
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -9094,7 +9094,7 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 				err = -EBADF;
 				break;
 			}
-			*io_get_tag_slot(data, up->offset + done) = tag;
+			*io_get_tag_slot(data, i) = tag;
 			io_fixed_file_set(file_slot, file);
 			err = io_sqe_file_register(ctx, file, i);
 			if (err) {