linux-kernel - Re: [PATCH v2] net: phy: micrel: fix crash when statistic requested for KSZ9031 phy

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Date:   Thu, 13 Apr 2017 13:56:57 -0500
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Sekhar Nori <nsekhar@...com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] net: phy: micrel: fix crash when statistic requested
 for KSZ9031 phy



On 04/13/2017 01:51 PM, Andrew Lunn wrote:
> On Wed, Apr 12, 2017 at 05:55:10PM -0500, Grygorii Strashko wrote:
>> Now the command:
>> 	ethtool --phy-statistics eth0
>> will cause system crash with meassage "Unable to handle kernel NULL pointer
>> dereference at virtual address 00000010" from:
>>
>>  (kszphy_get_stats) from [<c069f1d8>] (ethtool_get_phy_stats+0xd8/0x210)
>>  (ethtool_get_phy_stats) from [<c06a0738>] (dev_ethtool+0x5b8/0x228c)
>>  (dev_ethtool) from [<c06b5484>] (dev_ioctl+0x3fc/0x964)
>>  (dev_ioctl) from [<c0679f7c>] (sock_ioctl+0x170/0x2c0)
>>  (sock_ioctl) from [<c02419d4>] (do_vfs_ioctl+0xa8/0x95c)
>>  (do_vfs_ioctl) from [<c02422c4>] (SyS_ioctl+0x3c/0x64)
>>  (SyS_ioctl) from [<c0107d60>] (ret_fast_syscall+0x0/0x44)
>>
>> The reason: phy_driver structure for KSZ9031 phy has no .probe() callback
>> defined. As result, struct phy_device *phydev->priv pointer will not be
>> initializes (null).
>> This issue will affect also following phys:
>>  KSZ8795, KSZ886X, KSZ8873MLL, KSZ9031, KSZ9021, KSZ8061, KS8737
>>
>> Fix it by:
>> - adding .probe() = kszphy_probe() callback to KSZ9031, KSZ9021
>> phys. The kszphy_probe() can be re-used as it doesn't do any phy specific
>> settings.
>> - removing statistic callbacks from other phys (KSZ8795, KSZ886X,
>> KSZ8873MLL, KSZ8061, KS8737) as they doesn't have corresponding
>> statistic counters.
>>
>> Fixes: 2b2427d06426 ("phy: micrel: Add ethtool statistics counters")
>> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
>> ---
>> changes in v2:
>>  - probe callback added to KSZ9031, KSZ9021
>>  - statistic callback removed from KSZ8795, KSZ886X, KSZ8873MLL, KSZ8061, KS8737
>>
>> Link on v1:
>>  https://lkml.org/lkml/2017/4/10/1183
>>
>>  drivers/net/phy/micrel.c | 18 ++----------------
>>  1 file changed, 2 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
>> index 6742070..6f207e6 100644
>> --- a/drivers/net/phy/micrel.c
>> +++ b/drivers/net/phy/micrel.c
>> @@ -574,7 +574,6 @@ static int ksz9031_config_init(struct phy_device *phydev)
>>  				MII_KSZ9031RN_TX_DATA_PAD_SKEW, 4,
>>  				tx_data_skews, 4);
>>  	}
>> -
>>  	return ksz9031_center_flp_timing(phydev);
>>  }
>
> Hi Grygorii
>
> Whitespace changed like this should be in a separate patch, or not
> made at all.


Oh. sry i've missed it. Will resend


>
> Otherwise, thanks for looking at the datasheets and fixing this up.
>
> Reviewed-by: Andrew Lunn <andrew@...n.ch>


-- 
regards,
-grygorii