[PATCH 4.19 355/639] vfio/mdev: Avoid release parent reference during error path

[Greg Kroah-Hartman]

From: Parav Pandit <parav@xxxxxxxxxxxx>

[ Upstream commit 60e7f2c3fe9919cee9534b422865eed49f4efb15 ]

During mdev parent registration in mdev_register_device(),
if parent device is duplicate, it releases the reference of existing
parent device.
This is incorrect. Existing parent device should not be touched.

Fixes: 7b96953bc640 ("vfio: Mediated device Core driver")
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Reviewed-by: Kirti Wankhede <kwankhede@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Signed-off-by: Parav Pandit <parav@xxxxxxxxxxxx>
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/vfio/mdev/mdev_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 0212f0ee8aea7..8cfa712308773 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -182,6 +182,7 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
 	/* Check for duplicate */
 	parent = __find_parent_device(dev);
 	if (parent) {
+		parent = NULL;
 		ret = -EEXIST;
 		goto add_dev_err;
 	}
-- 
2.20.1