linux-kernel - RE: [PATCH net-next 2/2] net: phy: Add ability to debug RGMII connections

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Message-ID: <BN8PR12MB3266989D42B1C5B09E7053A3D3920@BN8PR12MB3266.namprd12.prod.outlook.com>
Date:   Wed, 16 Oct 2019 08:55:43 +0000
From:   Jose Abreu <Jose.Abreu@...opsys.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Andrew Lunn <andrew@...n.ch>,
        "David S. Miller" <davem@...emloft.net>,
        open list <linux-kernel@...r.kernel.org>,
        "hkallweit1@...il.com" <hkallweit1@...il.com>,
        "bcm-kernel-feedback-list@...adcom.com" 
        <bcm-kernel-feedback-list@...adcom.com>,
        "olteanv@...il.com" <olteanv@...il.com>,
        "rmk+kernel@...linux.org.uk" <rmk+kernel@...linux.org.uk>,
        "cphealy@...il.com" <cphealy@...il.com>
Subject: RE: [PATCH net-next 2/2] net: phy: Add ability to debug RGMII
 connections

From: Florian Fainelli <f.fainelli@...il.com>
Date: Oct/15/2019, 23:49:53 (UTC+00:00)

> The function phy_rgmii_debug_probe() could also be used by an Ethernet
> controller during its selftests routines instead of open-coding that
> part.

I can add it to stmmac selftests then :)

> +int phy_rgmii_debug_probe(struct phy_device *phydev)
> +{
> +	struct net_device *ndev = phydev->attached_dev;
> +	unsigned char operstate = ndev->operstate;
> +	phy_interface_t rgmii_modes[4] = {

This can be static.

> +		PHY_INTERFACE_MODE_RGMII,
> +		PHY_INTERFACE_MODE_RGMII_ID,
> +		PHY_INTERFACE_MODE_RGMII_RXID,
> +		PHY_INTERFACE_MODE_RGMII_TXID
> +	};
> +	struct phy_rgmii_debug_priv *priv;
> +	unsigned int i, count;
> +	int ret;
> +
> +	ret = phy_rgmii_can_debug(phydev);
> +	if (ret <= 0)
> +		return ret;
> +
> +	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	if (phy_rgmii_probes_type.af_packet_priv)
> +		return -EBUSY;

You are leaking "priv" here.

> +
> +	phy_rgmii_probes_type.af_packet_priv = priv;
> +	priv->phydev = phydev;
> +	INIT_WORK(&priv->work, phy_rgmii_probe_xmit_work);
> +	init_completion(&priv->compl);
> +
> +	/* We are now testing this network device */
> +	ndev->operstate = IF_OPER_TESTING;
> +
> +	dev_add_pack(&phy_rgmii_probes_type);
> +
> +	/* Determine where to start */
> +	for (i = 0; i < ARRAY_SIZE(rgmii_modes); i++) {
> +		if (phydev->interface == rgmii_modes[i])
> +			break;
> +	}
> +
> +	/* Now probe all modes */
> +	for (count = 0; count < ARRAY_SIZE(rgmii_modes); count++) {
> +		ret = phy_rgmii_probe_interface(priv, rgmii_modes[i]);
> +		if (ret == 0) {
> +			netdev_info(ndev, "Determined \"%s\" to be correct\n",
> +				    phy_modes(rgmii_modes[i]));
> +			break;
> +		}
> +		i = (i + 1) % ARRAY_SIZE(rgmii_modes);
> +	}
> +
> +	dev_remove_pack(&phy_rgmii_probes_type);
> +	kfree(priv);
> +	phy_rgmii_probes_type.af_packet_priv = NULL;

I think you should set af_packet_priv to NULL before freeing "priv" 
because of the "if ([...].af_packet_priv)" test, otherwise you can get 
use-after-free.

---
Thanks,
Jose Miguel Abreu