[PATCH v2] usb: misc: fix improper handling of refcount in uss720_probe()

From: Hangyu Hua
Date: Wed Apr 06 2022 - 22:40:27 EST


usb_put_dev shouldn't be called when uss720_probe succeeds because of
priv->usbdev. At the same time, priv->usbdev shouldn't be set to NULL
before destroy_priv in uss720_disconnect because usb_put_dev is in
destroy_priv.

Fix this by moving priv->usbdev = NULL after usb_put_dev.

Fixes: dcb4b8ad6a44 ("misc/uss720: fix memory leak in uss720_probe")
Signed-off-by: Hangyu Hua <hbh25y@xxxxxxxxx>
---

v2: fix a stupid UAF in the previous version.

drivers/usb/misc/uss720.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/usb/misc/uss720.c b/drivers/usb/misc/uss720.c
index 748139d26263..0be8efcda15d 100644
--- a/drivers/usb/misc/uss720.c
+++ b/drivers/usb/misc/uss720.c
@@ -71,6 +71,7 @@ static void destroy_priv(struct kref *kref)

dev_dbg(&priv->usbdev->dev, "destroying priv datastructure\n");
usb_put_dev(priv->usbdev);
+ priv->usbdev = NULL;
kfree(priv);
}

@@ -736,7 +737,6 @@ static int uss720_probe(struct usb_interface *intf,
parport_announce_port(pp);

usb_set_intfdata(intf, pp);
- usb_put_dev(usbdev);
return 0;

probe_abort:
@@ -754,7 +754,6 @@ static void uss720_disconnect(struct usb_interface *intf)
usb_set_intfdata(intf, NULL);
if (pp) {
priv = pp->private_data;
- priv->usbdev = NULL;
priv->pp = NULL;
dev_dbg(&intf->dev, "parport_remove_port\n");
parport_remove_port(pp);
--
2.25.1