On 11/11/2022 15:54, Yang Yingliang wrote:
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 <redacted>
---
Thanks for fixing it!
At first, I was slightly uneasy about calling device_del() and put_device() directly, i.e. it would be better not to worry about what's under the hood of device_unregister(). But 1) I don't see how else to fix it and 2) more importantly, I looked at the history of device_unregister() to see how frequently it changed. I can now rest easy :-)
Acked-by: Frederic Barrat <redacted>
Fred
quoted hunk ↗ jump to hunk
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: