linux-kernel - Re: [PATCH v2 net] net: phy: micrel: Fix warn: passing zero to PTR

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Date:   Tue, 19 Jul 2022 06:56:20 -0700
From:   Richard Cochran <richardcochran@...il.com>
To:     Divya Koppera <Divya.Koppera@...rochip.com>
Cc:     andrew@...n.ch, hkallweit1@...il.com, linux@...linux.org.uk,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, UNGLinuxDriver@...rochip.com,
        Madhuri.Sripada@...rochip.com
Subject: Re: [PATCH v2 net] net: phy: micrel: Fix warn: passing zero to
 PTR_ERR

On Tue, Jul 19, 2022 at 05:30:52PM +0530, Divya Koppera wrote:
> Handle the NULL pointer case
> 
> Fixes New smatch warnings:
> drivers/net/phy/micrel.c:2613 lan8814_ptp_probe_once() warn: passing zero to 'PTR_ERR'
> 
> vim +/PTR_ERR +2613 drivers/net/phy/micrel.c
> 
> Reported-by: kernel test robot <lkp@...el.com>
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Fixes: ece19502834d ("net: phy: micrel: 1588 support for LAN8814 phy")
> Signed-off-by: Divya Koppera <Divya.Koppera@...rochip.com>
> ---
> v1 -> v2:
> - Handled NULL pointer case
> - Changed subject line with net-next to net

This is not a genuine bug fix, and so it should target next-next.

> ---
>  drivers/net/phy/micrel.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> index e78d0bf69bc3..6be6ee156f40 100644
> --- a/drivers/net/phy/micrel.c
> +++ b/drivers/net/phy/micrel.c
> @@ -2812,12 +2812,16 @@ static int lan8814_ptp_probe_once(struct phy_device *phydev)
>  
>  	shared->ptp_clock = ptp_clock_register(&shared->ptp_clock_info,
>  					       &phydev->mdio.dev);
> -	if (IS_ERR_OR_NULL(shared->ptp_clock)) {
> +	if (IS_ERR(shared->ptp_clock)) {
>  		phydev_err(phydev, "ptp_clock_register failed %lu\n",
>  			   PTR_ERR(shared->ptp_clock));
>  		return -EINVAL;
>  	}
>  
> +	/* Check if PHC support is missing at the configuration level */
> +	if (!shared->ptp_clock)
> +		return 0;

This is cause a NULL pointer de-reference in lan8814_ts_info()
when it calls 

	info->phc_index = ptp_clock_index(shared->ptp_clock);

> +
>  	phydev_dbg(phydev, "successfully registered ptp clock\n");
>  
>  	shared->phydev = phydev;
> -- 
> 2.17.1
> 

Thanks,
Richard