[PATCH 6.1 0720/1146] cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter()

Greg Kroah-Hartman
2022-12-28T16:29:05Z

From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit 61c80d1c3833e196256fb060382db94f24d3d9a7 ]

If device_register() fails in cxl_register_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: 14baf4d9c739 ("cxl: Add guest-specific code")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Acked-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
Link: https://lore.kernel.org/r/20221111145440.2426970-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/misc/cxl/guest.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
index 375f692ae9d6..fb95a2d5cef4 100644
--- a/drivers/misc/cxl/guest.c
+++ b/drivers/misc/cxl/guest.c
@@ -965,10 +965,10 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n
* 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;

/*
* pHyp doesn't expose the programming models supported by the
@@ -984,7 +984,7 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n
afu->modes_supported = CXL_MODE_DIRECTED;

if ((rc = cxl_afu_select_best_mode(afu)))
- goto err_put2;
+ goto err_remove_sysfs;

adapter->afu[afu->slice] = afu;

@@ -1004,10 +1004,12 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n

return 0;

-err_put2:
+err_remove_sysfs:
cxl_sysfs_afu_remove(afu);
-err_put1:
- device_unregister(&afu->dev);
+err_del_dev:
+ device_del(&afu->dev);
+err_put_dev:
+ put_device(&afu->dev);
free = false;
guest_release_serr_irq(afu);
err2:
@@ -1141,18 +1143,20 @@ struct cxl *cxl_guest_init_adapter(struct device_node *np, struct platform_devic
* 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 the adapter is configured */
cxl_adapter_context_unlock(adapter);

return adapter;

-err_put1:
- device_unregister(&adapter->dev);
+err_del_dev:
+ device_del(&adapter->dev);
+err_put_dev:
+ put_device(&adapter->dev);
free = false;
cxl_guest_remove_chardev(adapter);
err1:
--
2.35.1