netdev - Re: [PATCH net-next 1/3] ethtool: Ensure new ring parameters are within bounds during SRINGPARAM

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Date:   Tue, 9 Jan 2018 09:30:05 +0200
From:   Tariq Toukan <tariqt@...lanox.com>
To:     Jakub Kicinski <kubakici@...pl>, Tariq Toukan <tariqt@...lanox.com>
Cc:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Eran Ben Elisha <eranbe@...lanox.com>,
        Eugenia Emantayev <eugenia@...lanox.com>
Subject: Re: [PATCH net-next 1/3] ethtool: Ensure new ring parameters are
 within bounds during SRINGPARAM



On 09/01/2018 4:23 AM, Jakub Kicinski wrote:
> On Mon,  8 Jan 2018 16:00:24 +0200, Tariq Toukan wrote:
>> From: Eugenia Emantayev <eugenia@...lanox.com>
>>
>> Add a sanity check to ensure that all requested ring parameters
>> are within bounds, which should reduce errors in driver implementation.
> 
> (y)
> 
>> Signed-off-by: Eugenia Emantayev <eugenia@...lanox.com>
>> Signed-off-by: Tariq Toukan <tariqt@...lanox.com>
>> ---
>>   net/core/ethtool.c | 13 +++++++++++--
>>   1 file changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/core/ethtool.c b/net/core/ethtool.c
>> index 50a79203043b..9ea7cd52fde0 100644
>> --- a/net/core/ethtool.c
>> +++ b/net/core/ethtool.c
>> @@ -1704,14 +1704,23 @@ static int ethtool_get_ringparam(struct net_device *dev, void __user *useraddr)
>>   
>>   static int ethtool_set_ringparam(struct net_device *dev, void __user *useraddr)
>>   {
>> -	struct ethtool_ringparam ringparam;
>> +	struct ethtool_ringparam ringparam, max = { .cmd = ETHTOOL_GRINGPARAM };
>>   
>> -	if (!dev->ethtool_ops->set_ringparam)
>> +	if (!dev->ethtool_ops->set_ringparam || !dev->ethtool_ops->get_ringparam)
>>   		return -EOPNOTSUPP;
>>   
>>   	if (copy_from_user(&ringparam, useraddr, sizeof(ringparam)))
>>   		return -EFAULT;
>>   
>> +	dev->ethtool_ops->get_ringparam(dev, &max);
> 
> Perhaps check the return value here?  It's pretty unlikely but
> get_ringparam may fail.
> 

get_ringparam NDO returns void.

>> +	/* ensure new ring parameters are within the maximums */
>> +	if (ringparam.rx_pending > max.rx_max_pending ||
>> +	    ringparam.rx_mini_pending > max.rx_mini_max_pending ||
>> +	    ringparam.rx_jumbo_pending > max.rx_jumbo_max_pending ||
>> +	    ringparam.tx_pending > max.tx_max_pending)
>> +		return -EINVAL;
>> +
>>   	return dev->ethtool_ops->set_ringparam(dev, &ringparam);
>>   }
>>