netdev - [PATCH net-next] net: ftgmac100: Fix potential NULL dereference in error handling

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Message-ID:
 <SEYPR06MB51342F3EC5D457CC512937259D9E2@SEYPR06MB5134.apcprd06.prod.outlook.com>
Date: Fri, 6 Sep 2024 06:06:14 +0000
From: Jacky Chou <jacky_chou@...eedtech.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Uwe Kleine-König
	<u.kleine-koenig@...gutronix.de>, Jacob Keller <jacob.e.keller@...el.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: [PATCH net-next] net: ftgmac100: Fix potential NULL dereference in
 error handling

Hello,

> 
> We might not have a phy so we need to check for NULL before calling
> phy_stop(netdev->phydev) or it could lead to an Oops.
> 
> Fixes: e24a6c874601 ("net: ftgmac100: Get link speed and duplex for NC-SI")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
>  drivers/net/ethernet/faraday/ftgmac100.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/faraday/ftgmac100.c
> b/drivers/net/ethernet/faraday/ftgmac100.c
> index f3cc14cc757d..0e873e6f60d6 100644
> --- a/drivers/net/ethernet/faraday/ftgmac100.c
> +++ b/drivers/net/ethernet/faraday/ftgmac100.c
> @@ -1565,7 +1565,8 @@ static int ftgmac100_open(struct net_device
> *netdev)
>  	return 0;
> 
>  err_ncsi:
> -	phy_stop(netdev->phydev);
> +	if (netdev->phydev)
> +		phy_stop(netdev->phydev);
When using " use-ncsi" property, the driver will register a fixed-link phy device and 
bind to netdev at probe stage.

if (np && of_get_property(np, "use-ncsi", NULL)) {

		......

		phydev = fixed_phy_register(PHY_POLL, &ncsi_phy_status, NULL);
		err = phy_connect_direct(netdev, phydev, ftgmac100_adjust_link,
					 PHY_INTERFACE_MODE_MII);
		if (err) {
			dev_err(&pdev->dev, "Connecting PHY failed\n");
			goto err_phy_connect;
		}
} else if (np && of_phy_is_fixed_link(np)) {

Therefore, it does not need to check if the point is NULL in this error handling.
Thanks.

>  	napi_disable(&priv->napi);
>  	netif_stop_queue(netdev);
>  err_alloc:
> --
> 2.45.2