[PATCH v2] usb: cdns3: Fix PCI device reference leak in cdns3_pci_probe()

[Ma Ke]

cdns3_get_second_fun() looks up the second PCI function with
pci_get_device(), which returns the device with a reference held, and
hands it back to its callers.  Neither cdns3_pci_probe() nor
cdns3_pci_remove() ever drops that reference, so the second function's
pci_dev can never be released.

The cdnsp-pci.c driver handles the same situation correctly.
cdnsp_pci_probe() jumps to a 'put_pci:' label that calls
pci_dev_put(), and cdnsp_pci_remove() calls pci_dev_put() as well.

While at it, also add the missing NULL check in cdns3_pci_remove().
pci_is_enabled() dereferences its argument, so if
cdns3_get_second_fun() returns NULL, the current code may crash.
cdnsp_pci_remove() guards with "!func ||".

cdns3_pci_probe() gained one more return path since this was first
posted: commit e5052f2c5c73 ("usb: cdns3: Fix NULL pointer
dereference in cdns3_pci_probe") added a -EPROBE_DEFER return after
the reference has been taken, so that path needs to drop it as well.

Found by code review.

Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ma Ke <make_ruc2021@xxxxxxx>
---
Changes in v2:
- rebase on current mainline. cdns3_pci_probe() gained a -EPROBE_DEFER
  path in e5052f2c5c73 that returns after the reference has been taken, 
  so it has to drop it too.
---
 drivers/usb/cdns3/cdns3-pci-wrap.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/cdns3/cdns3-pci-wrap.c b/drivers/usb/cdns3/cdns3-pci-wrap.c
index fd06a3d8e638..7799349bba77 100644
--- a/drivers/usb/cdns3/cdns3-pci-wrap.c
+++ b/drivers/usb/cdns3/cdns3-pci-wrap.c
@@ -89,7 +89,7 @@ static int cdns3_pci_probe(struct pci_dev *pdev,
 	err = pcim_enable_device(pdev);
 	if (err) {
 		dev_err(&pdev->dev, "Enabling PCI device has failed %d\n", err);
-		return err;
+		goto put_pci;
 	}
 
 	pci_set_master(pdev);
@@ -99,12 +99,15 @@ static int cdns3_pci_probe(struct pci_dev *pdev,
 		if (!wrap) {
 			dev_err(&pdev->dev,
 				"second function not initialized, retrying\n");
-			return -EPROBE_DEFER;
+			err = -EPROBE_DEFER;
+			goto put_pci;
 		}
 	} else {
 		wrap = kzalloc_obj(*wrap);
-		if (!wrap)
-			return -ENOMEM;
+		if (!wrap) {
+			err = -ENOMEM;
+			goto put_pci;
+		}
 	}
 
 	res = wrap->dev_res;
@@ -165,11 +168,13 @@ static int cdns3_pci_probe(struct pci_dev *pdev,
 		if (IS_ERR(wrap->plat_dev)) {
 			err = PTR_ERR(wrap->plat_dev);
 			kfree(wrap);
-			return err;
+			goto put_pci;
 		}
 	}
 
 	pci_set_drvdata(pdev, wrap);
+put_pci:
+	pci_dev_put(func);
 	return err;
 }
 
@@ -184,8 +189,10 @@ static void cdns3_pci_remove(struct pci_dev *pdev)
 	if (wrap->devfn == pdev->devfn)
 		platform_device_unregister(wrap->plat_dev);
 
-	if (!pci_is_enabled(func))
+	if (!func || !pci_is_enabled(func))
 		kfree(wrap);
+
+	pci_dev_put(func);
 }
 
 static const struct pci_device_id cdns3_pci_ids[] = {
-- 
2.43.0