hwrng: amd - Fix PCI device refcount leak

[ Upstream commit ecadb5b ]

for_each_pci_dev() is implemented by pci_get_device(). The comment of
pci_get_device() says that it will increase the reference count for the
returned pci_dev and also decrease the reference count for the input
pci_dev @from if it is not NULL.

If we break for_each_pci_dev() loop with pdev not NULL, we need to call
pci_dev_put() to decrease the reference count. Add the missing
pci_dev_put() for the normal and error path.

Fixes: 96d63c0 ("[PATCH] Add AMD HW RNG driver")
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/char/hw_random/amd-rng.c

@@ -143,15 +143,19 @@ static int __init mod_init(void)
 found:
 	err = pci_read_config_dword(pdev, 0x58, &pmbase);
 	if (err)
-		return err;
+		goto put_dev;
 
 	pmbase &= 0x0000FF00;
-	if (pmbase == 0)
-		return -EIO;
+	if (pmbase == 0) {
+		err = -EIO;
+		goto put_dev;
+	}
 
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
-	if (!priv)
-		return -ENOMEM;
+	if (!priv) {
+		err = -ENOMEM;
+		goto put_dev;
+	}
 
 	if (!request_region(pmbase + PMBASE_OFFSET, PMBASE_SIZE, DRV_NAME)) {
 		dev_err(&pdev->dev, DRV_NAME " region 0x%x already in use!\n",
@@ -185,6 +189,8 @@ static int __init mod_init(void)
 	release_region(pmbase + PMBASE_OFFSET, PMBASE_SIZE);
 out:
 	kfree(priv);
+put_dev:
+	pci_dev_put(pdev);
 	return err;
 }
 
@@ -200,6 +206,8 @@ static void __exit mod_exit(void)
 
 	release_region(priv->pmbase + PMBASE_OFFSET, PMBASE_SIZE);
 
+	pci_dev_put(priv->pcidev);
+
 	kfree(priv);
 }