uio_hv_generic: Fix another memory leak in error handling paths

Memory allocated by 'vmbus_alloc_ring()' at the beginning of the probe
function is never freed in the error handling path.

Add the missing 'vmbus_free_ring()' call.

Note that it is already freed in the .remove function.

Fixes: cdfa835 ("uio_hv_generic: defer opening vmbus until first use")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/0d86027b8eeed8e6360bc3d52bcdb328ff9bdca1.1620544055.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: tititiou36

drivers/uio/uio_hv_generic.c

@@ -291,7 +291,7 @@ hv_uio_probe(struct hv_device *dev,
 	pdata->recv_buf = vzalloc(RECV_BUFFER_SIZE);
 	if (pdata->recv_buf == NULL) {
 		ret = -ENOMEM;
-		goto fail_close;
+		goto fail_free_ring;
 	}
 
 	ret = vmbus_establish_gpadl(channel, pdata->recv_buf,
@@ -351,6 +351,8 @@ hv_uio_probe(struct hv_device *dev,
 
 fail_close:
 	hv_uio_cleanup(dev, pdata);
+fail_free_ring:
+	vmbus_free_ring(dev->channel);
 
 	return ret;
 }