[PATCH net] net: ti: icssg_prueth: Fix NULL pointer dereference in prueth_probe()

[Simon Horman]

+ Andrew Lunn, Diogo Ivo, Vignesh Raghavendra
  Not trimming reply to provide context for these people

On Tue, May 21, 2024 at 02:44:11PM +0200, Romain Gantois wrote:
> In the prueth_probe() function, if one of the calls to emac_phy_connect()
> fails due to of_phy_connect() returning NULL, then the subsequent call to
> phy_attached_info() will dereference a NULL pointer.
> 
> Check the return code of emac_phy_connect and fail cleanly if there is an
> error.
> 
> Fixes: 128d5874c082 ("net: ti: icssg-prueth: Add ICSSG ethernet driver")
> Cc: stable at vger.kernel.org
> Signed-off-by: Romain Gantois <romain.gantois at bootlin.com>

For Networking patches, please consider seeding the CC
list using ./scripts/get_maintainer.pl this.patch.
I've added the people who seemed to be missing.

The patch itself looks good to me.

Reviewed-by: Simon Horman <horms at kernel.org>

> ---
> Hello everyone,
> 
> There is a possible NULL pointer dereference in the prueth_probe() function of
> the icssg_prueth driver. I discovered this while testing a platform with one
> PRUETH MAC enabled out of the two available.
> 
> These are the requirements to reproduce the bug:
> 
> prueth_probe() is called
> either eth0_node or eth1_node is not NULL
> in emac_phy_connect: of_phy_connect() returns NULL
> 
> Then, the following leads to the NULL pointer dereference:
> 
> prueth->emac[PRUETH_MAC0]->ndev->phydev is set to NULL
> prueth->emac[PRUETH_MAC0]->ndev->phydev is passed to phy_attached_info()
> -> phy_attached_print() dereferences phydev which is NULL
> 
> This series provides a fix by checking the return code of emac_phy_connect().
> 
> Best Regards,
> 
> Romain
> ---
>  drivers/net/ethernet/ti/icssg/icssg_prueth.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> index 7c9e9518f555a..1ea3fbd5e954e 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> @@ -1039,7 +1039,12 @@ static int prueth_probe(struct platform_device *pdev)
>  
>  		prueth->registered_netdevs[PRUETH_MAC0] = prueth->emac[PRUETH_MAC0]->ndev;
>  
> -		emac_phy_connect(prueth->emac[PRUETH_MAC0]);
> +		ret = emac_phy_connect(prueth->emac[PRUETH_MAC0]);
> +		if (ret) {
> +			dev_err(dev,
> +				"can't connect to MII0 PHY, error -%d", ret);
> +			goto netdev_unregister;
> +		}
>  		phy_attached_info(prueth->emac[PRUETH_MAC0]->ndev->phydev);
>  	}
>  
> @@ -1051,7 +1056,12 @@ static int prueth_probe(struct platform_device *pdev)
>  		}
>  
>  		prueth->registered_netdevs[PRUETH_MAC1] = prueth->emac[PRUETH_MAC1]->ndev;
> -		emac_phy_connect(prueth->emac[PRUETH_MAC1]);
> +		ret = emac_phy_connect(prueth->emac[PRUETH_MAC1]);
> +		if (ret) {
> +			dev_err(dev,
> +				"can't connect to MII1 PHY, error %d", ret);
> +			goto netdev_unregister;
> +		}
>  		phy_attached_info(prueth->emac[PRUETH_MAC1]->ndev->phydev);
>  	}
>  
> 
> ---
> base-commit: e4a87abf588536d1cdfb128595e6e680af5cf3ed
> change-id: 20240521-icssg-prueth-fix-03b03064c5ce
> 
> Best regards,
> -- 
> Romain Gantois <romain.gantois at bootlin.com>
> 
>