io_uring/net: don't pick multiple buffers for non-bundle send

If a send is issued marked with IOSQE_BUFFER_SELECT for selecting a
buffer, unless it's a bundle, it should not select multiple buffers.

Cc: stable@vger.kernel.org
Fixes: a05d1f62 ("io_uring/net: support bundles for send")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/net.c

@@ -601,17 +601,18 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
 			.iovs = &kmsg->fast_iov,
 			.max_len = INT_MAX,
 			.nr_iovs = 1,
-			.mode = KBUF_MODE_EXPAND,
 		};
 
 		if (kmsg->free_iov) {
 			arg.nr_iovs = kmsg->free_iov_nr;
 			arg.iovs = kmsg->free_iov;
-			arg.mode |= KBUF_MODE_FREE;
+			arg.mode = KBUF_MODE_FREE;
 		}
 
 		if (!(sr->flags & IORING_RECVSEND_BUNDLE))
 			arg.nr_iovs = 1;
+		else
+			arg.mode |= KBUF_MODE_EXPAND;
 
 		ret = io_buffers_select(req, &arg, issue_flags);
 		if (unlikely(ret < 0))