cxl: fix possible null-ptr-deref in cxl_pci_init_afu|adapter()

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 <yangyingliang@huawei.com>
Acked-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221111145440.2426970-2-yangyingliang@huawei.com

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 62385a529d86986e228dde8be2e96aeaaf44fabd..0ff944860dda988e3af5f8d2ed64ebe55e87a97f 100644 (file)
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1165,10 +1165,10 @@ 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;
 
@@ -1177,10 +1177,12 @@ 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:
@@ -1668,23 +1670,25 @@ 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: