[PATCH 2/2] cxl: fix possible null-ptr-deref in cxl_pci_init_afu|adapter()

[Yang Yingliang]

If device_register() fails in cxl_pci_afu|adapter(), the device
is not added, device_unregister() can not be called in the error
path, otherwise it will cause a null-ptr-deref because of removing
not added device.

As comment of device_register() says, it should use put_device() to give
up the reference in the error path. So split device_unregister() into
device_del() and put_device(), then goes to put dev when register fails.

Fixes: f204e0b8cedd ("cxl: Driver code for powernv PCIe based cards for 
userspace access")
Signed-off-by: Yang Yingliang <yangyingli...@huawei.com>
---
 drivers/misc/cxl/pci.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 3de0aea62ade..6d495d641c95 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1164,10 +1164,10 @@ static int pci_init_afu(struct cxl *adapter, int slice, 
struct pci_dev *dev)
         * if it returns an error!
         */
        if ((rc = cxl_register_afu(afu)))
-               goto err_put1;
+               goto err_put_dev;
 
        if ((rc = cxl_sysfs_afu_add(afu)))
-               goto err_put1;
+               goto err_del_dev;
 
        adapter->afu[afu->slice] = afu;
 
@@ -1176,10 +1176,12 @@ static int pci_init_afu(struct cxl *adapter, int slice, 
struct pci_dev *dev)
 
        return 0;
 
-err_put1:
+err_del_dev:
+       device_del(&afu->dev);
+err_put_dev:
        pci_deconfigure_afu(afu);
        cxl_debugfs_afu_remove(afu);
-       device_unregister(&afu->dev);
+       put_device(&afu->dev);
        return rc;
 
 err_free_native:
@@ -1667,23 +1669,25 @@ static struct cxl *cxl_pci_init_adapter(struct pci_dev 
*dev)
         * even if it returns an error!
         */
        if ((rc = cxl_register_adapter(adapter)))
-               goto err_put1;
+               goto err_put_dev;
 
        if ((rc = cxl_sysfs_adapter_add(adapter)))
-               goto err_put1;
+               goto err_del_dev;
 
        /* Release the context lock as adapter is configured */
        cxl_adapter_context_unlock(adapter);
 
        return adapter;
 
-err_put1:
+err_del_dev:
+       device_del(&adapter->dev);
+err_put_dev:
        /* This should mirror cxl_remove_adapter, except without the
         * sysfs parts
         */
        cxl_debugfs_adapter_remove(adapter);
        cxl_deconfigure_adapter(adapter);
-       device_unregister(&adapter->dev);
+       put_device(&adapter->dev);
        return ERR_PTR(rc);
 
 err_release:
-- 
2.25.1