linux-kernel - Re: [PATCH] can: sja1000: plx_pci: fix error handling path in plx_pci_add

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Date:   Thu, 24 Nov 2022 15:46:38 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Zhang Changzhong <zhangchangzhong@...wei.com>
Cc:     Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Julia Lawall <julia@...u.dk>,
        Pavel Cheblakov <P.B.Cheblakov@....nsk.su>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] can: sja1000: plx_pci: fix error handling path in
 plx_pci_add_card()

On 21.11.2022 19:10:30, Zhang Changzhong wrote:
> If pci_iomap() or register_sja1000dev() fails, netdev will not be
> registered, but plx_pci_del_card() still deregisters the netdev.
> 
> To avoid this, let's free the netdev and clear card->net_dev[i] before
> calling plx_pci_del_card(). In addition, add the missing pci_iounmap()
> when the channel does not exist.
> 
> Compile tested only.
> 
> Fixes: 951f2f960e5b ("drivers/net/can/sja1000/plx_pci.c: eliminate double free")
> Fixes: 24c4a3b29255 ("can: add support for CAN interface cards based on the PLX90xx PCI bridge")
> Signed-off-by: Zhang Changzhong <zhangchangzhong@...wei.com>
> ---
>  drivers/net/can/sja1000/plx_pci.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/can/sja1000/plx_pci.c b/drivers/net/can/sja1000/plx_pci.c
> index 5de1ebb..1158f5a 100644
> --- a/drivers/net/can/sja1000/plx_pci.c
> +++ b/drivers/net/can/sja1000/plx_pci.c
> @@ -678,6 +678,8 @@ static int plx_pci_add_card(struct pci_dev *pdev,
>  		if (!addr) {
>  			err = -ENOMEM;
>  			dev_err(&pdev->dev, "Failed to remap BAR%d\n", cm->bar);
> +			free_sja1000dev(dev);
> +			card->net_dev[i] = NULL;
>  			goto failure_cleanup;
>  		}
>  
> @@ -699,6 +701,9 @@ static int plx_pci_add_card(struct pci_dev *pdev,
>  			if (err) {
>  				dev_err(&pdev->dev, "Registering device failed "
>  					"(err=%d)\n", err);
> +				pci_iounmap(pdev, priv->reg_base);
> +				free_sja1000dev(dev);
> +				card->net_dev[i] = NULL;
>  				goto failure_cleanup;
>  			}
>  
> @@ -710,6 +715,7 @@ static int plx_pci_add_card(struct pci_dev *pdev,
>  		} else {
>  			dev_err(&pdev->dev, "Channel #%d not detected\n",
>  				i + 1);
> +			pci_iounmap(pdev, priv->reg_base);
>  			free_sja1000dev(dev);
>  			card->net_dev[i] = NULL;

There's quite some cleanup code doubling. Can you introduce a goto style
cleanup?

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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