The mei_ace driver contains a device reference count leak in
mei_ace_setup_dev_link() where device_find_child_by_name() increases
the reference count of the found device but this reference is not
properly decreased in the success path. Add put_device() in
mei_ace_setup_dev_link() and delete put_device() in mei_ace_remove(),
which ensures that the reference count of the device is correctly
managed regardless of whether the probe is successful or fails.

Found by code review.

Cc: stable@vger.kernel.org
Fixes: 78876f71b3e9 ("media: pci: intel: ivsc: Add ACE submodule")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
Changes in v2:
- modified the put_device() operations and the patch title as suggestions.
---
 drivers/media/pci/intel/ivsc/mei_ace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/pci/intel/ivsc/mei_ace.c b/drivers/media/pci/intel/ivsc/mei_ace.c
index 98310b8511b1..bb57656fc85a 100644
--- a/drivers/media/pci/intel/ivsc/mei_ace.c
+++ b/drivers/media/pci/intel/ivsc/mei_ace.c
@@ -420,6 +420,7 @@ static int mei_ace_setup_dev_link(struct mei_ace *ace)
 		goto err_put;
 	}
 
+	put_device(csi_dev);
 	ace->csi_dev = csi_dev;
 
 	return 0;
@@ -522,7 +523,6 @@ static void mei_ace_remove(struct mei_cl_device *cldev)
 	cancel_work_sync(&ace->work);
 
 	device_link_del(ace->csi_link);
-	put_device(ace->csi_dev);
 
 	pm_runtime_disable(&cldev->dev);
 	pm_runtime_set_suspended(&cldev->dev);
-- 
2.17.1

Hi Ma,

On Mon, Sep 22, 2025 at 05:43:35PM +0800, Ma Ke wrote:
> The mei_ace driver contains a device reference count leak in
> mei_ace_setup_dev_link() where device_find_child_by_name() increases
> the reference count of the found device but this reference is not
> properly decreased in the success path. Add put_device() in
> mei_ace_setup_dev_link() and delete put_device() in mei_ace_remove(),
> which ensures that the reference count of the device is correctly
> managed regardless of whether the probe is successful or fails.
> 
> Found by code review.
> 
> Cc: stable@vger.kernel.org
> Fixes: 78876f71b3e9 ("media: pci: intel: ivsc: Add ACE submodule")

As this isn't a bug fix, I don't think we need these two tags. This should
be taken into account in the subject and commit message as well.

> Signed-off-by: Ma Ke <make24@iscas.ac.cn>
> ---
> Changes in v2:
> - modified the put_device() operations and the patch title as suggestions.
> ---
>  drivers/media/pci/intel/ivsc/mei_ace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/pci/intel/ivsc/mei_ace.c b/drivers/media/pci/intel/ivsc/mei_ace.c
> index 98310b8511b1..bb57656fc85a 100644
> --- a/drivers/media/pci/intel/ivsc/mei_ace.c
> +++ b/drivers/media/pci/intel/ivsc/mei_ace.c
> @@ -420,6 +420,7 @@ static int mei_ace_setup_dev_link(struct mei_ace *ace)
>  		goto err_put;
>  	}
>  
> +	put_device(csi_dev);

You can do this right after calling device_link_add().

>  	ace->csi_dev = csi_dev;
>  
>  	return 0;
> @@ -522,7 +523,6 @@ static void mei_ace_remove(struct mei_cl_device *cldev)
>  	cancel_work_sync(&ace->work);
>  
>  	device_link_del(ace->csi_link);
> -	put_device(ace->csi_dev);
>  
>  	pm_runtime_disable(&cldev->dev);
>  	pm_runtime_set_suspended(&cldev->dev);

-- 
Regards,

Sakari Ailus