s390/ism: add release function for struct device

According to device_release() in /drivers/base/core.c,
a device without a release function is a broken device
and must be fixed.

The current code directly frees the device after calling device_add()
without waiting for other kernel parts to release their references.
Thus, a reference could still be held to a struct device,
e.g., by sysfs, leading to potential use-after-free
issues if a proper release function is not set.

Fixes: 8c81ba2 ("net/smc: De-tangle ism and smc device initialization")
Reviewed-by: Alexandra Winter <[email protected]>
Reviewed-by: Wenjia Zhang <[email protected]>
Signed-off-by: Julian Ruess <[email protected]>
Signed-off-by: Alexandra Winter <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: juru1234

drivers/s390/net/ism_drv.c

@@ -588,6 +588,15 @@ static int ism_dev_init(struct ism_dev *ism)
 	return ret;
 }
 
+static void ism_dev_release(struct device *dev)
+{
+	struct ism_dev *ism;
+
+	ism = container_of(dev, struct ism_dev, dev);
+
+	kfree(ism);
+}
+
 static int ism_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
 	struct ism_dev *ism;
@@ -601,6 +610,7 @@ static int ism_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	dev_set_drvdata(&pdev->dev, ism);
 	ism->pdev = pdev;
 	ism->dev.parent = &pdev->dev;
+	ism->dev.release = ism_dev_release;
 	device_initialize(&ism->dev);
 	dev_set_name(&ism->dev, dev_name(&pdev->dev));
 	ret = device_add(&ism->dev);
@@ -637,7 +647,7 @@ static int ism_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	device_del(&ism->dev);
 err_dev:
 	dev_set_drvdata(&pdev->dev, NULL);
-	kfree(ism);
+	put_device(&ism->dev);
 
 	return ret;
 }
@@ -682,7 +692,7 @@ static void ism_remove(struct pci_dev *pdev)
 	pci_disable_device(pdev);
 	device_del(&ism->dev);
 	dev_set_drvdata(&pdev->dev, NULL);
-	kfree(ism);
+	put_device(&ism->dev);
 }
 
 static struct pci_driver ism_driver = {