io_uring: re-set iov base/len for buffer select retry

We already have the buffer selected, but we should set the iter list
again.

Cc: stable@vger.kernel.org # v5.7
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -2363,8 +2363,14 @@ static ssize_t __io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov,
 static ssize_t io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov,
 				    bool needs_lock)
 {
-	if (req->flags & REQ_F_BUFFER_SELECTED)
+	if (req->flags & REQ_F_BUFFER_SELECTED) {
+		struct io_buffer *kbuf;
+
+		kbuf = (struct io_buffer *) (unsigned long) req->rw.addr;
+		iov[0].iov_base = u64_to_user_ptr(kbuf->addr);
+		iov[0].iov_len = kbuf->len;
 		return 0;
+	}
 	if (!req->rw.len)
 		return 0;
 	else if (req->rw.len > 1)