[PATCH net] s390/ism: add release function for struct device

Alexandra Winter
2025-02-14T12:01:50Z

From: Julian Ruess <julianr@linux.ibm.com>

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: 8c81ba20349d ("net/smc: De-tangle ism and smc device initialization")
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>
Signed-off-by: Julian Ruess <julianr@linux.ibm.com>
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
---
drivers/s390/net/ism_drv.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/net/ism_drv.c b/drivers/s390/net/ism_drv.c
index e36e3ea165d3..2f34761e6413 100644
--- a/drivers/s390/net/ism_drv.c
+++ b/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 = {
--
2.45.2