Re: [PATCH v2] NTB: fix possible name leak in ntb_register_device()

[Manivannan Sadhasivam <mani@kernel.org>]

On Thu, Nov 30, 2023 at 08:28:53PM +0800, Yang Yingliang wrote:
> From: Yang Yingliang <yangyingliang@huawei.com>
> 
> If device_register() returns error in ntb_register_device(),
> the name allocated by dev_set_name() need be freed. As comment
> of device_register() says, it should use put_device() to give
> up the reference in the error path. So fix this by calling
> put_device(), then the name can be freed in kobject_cleanup().
> 
> Remove the outside put_device() in pci_vntb_probe() and return
> the error code.
> 
> Fixes: a1bd3baeb2f1 ("NTB: Add NTB hardware abstraction layer")
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> ---
> v1 -> v2:
>    return the error code in the error path in pci_vntb_probe().
> ---
>  drivers/ntb/core.c                            | 8 +++++++-
>  drivers/pci/endpoint/functions/pci-epf-vntb.c | 8 ++------
>  2 files changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/ntb/core.c b/drivers/ntb/core.c
> index 27dd93deff6e..d702bee78082 100644
> --- a/drivers/ntb/core.c
> +++ b/drivers/ntb/core.c
> @@ -100,6 +100,8 @@ EXPORT_SYMBOL(ntb_unregister_client);
>  
>  int ntb_register_device(struct ntb_dev *ntb)
>  {
> +	int ret;
> +
>  	if (!ntb)
>  		return -EINVAL;
>  	if (!ntb->pdev)
> @@ -120,7 +122,11 @@ int ntb_register_device(struct ntb_dev *ntb)
>  	ntb->ctx_ops = NULL;
>  	spin_lock_init(&ntb->ctx_lock);
>  
> -	return device_register(&ntb->dev);
> +	ret = device_register(&ntb->dev);
> +	if (ret)
> +		put_device(&ntb->dev);
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL(ntb_register_device);
>  
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index 3f60128560ed..c6f07722cbac 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -1272,21 +1272,17 @@ static int pci_vntb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
>  	if (ret) {
>  		dev_err(dev, "Cannot set DMA mask\n");
> -		return -EINVAL;
> +		return ret;

A patch should do only one thing at a time. You should not sneak changes like
this even though it is valid.

- Mani

>  	}
>  
>  	ret = ntb_register_device(&ndev->ntb);
>  	if (ret) {
>  		dev_err(dev, "Failed to register NTB device\n");
> -		goto err_register_dev;
> +		return ret;
>  	}
>  
>  	dev_dbg(dev, "PCI Virtual NTB driver loaded\n");
>  	return 0;
> -
> -err_register_dev:
> -	put_device(&ndev->ntb.dev);
> -	return -EINVAL;
>  }
>  
>  static struct pci_device_id pci_vntb_table[] = {
> -- 
> 2.25.1
> 

-- 
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