netdev - Re: [net-next-2.6 PATCH 3/3 RFC] macvtap: Add support for TUNSETTXFILTER

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Message-ID: <CA8E602D.33B8C%roprabhu@cisco.com>
Date:	Thu, 08 Sep 2011 12:06:05 -0700
From:	Roopa Prabhu <roprabhu@...co.com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	<netdev@...r.kernel.org>, <dragos.tatulea@...il.com>,
	<mst@...hat.com>, <dwang2@...co.com>, <benve@...co.com>,
	<kaber@...sh.net>, <sri@...ibm.com>
Subject: Re: [net-next-2.6 PATCH 3/3 RFC] macvtap: Add support for
 TUNSETTXFILTER

On 9/8/11 9:25 AM, "Arnd Bergmann" <arnd@...db.de> wrote:

> On Wednesday 07 September 2011, Roopa Prabhu wrote:
>> From: Roopa Prabhu <roprabhu@...co.com>
>> 
>> This patch adds support for TUNSETTXFILTER. Calls macvlan set filter function
>> with address list and flags received via TUNSETTXFILTER.
>> 
>> Signed-off-by: Roopa Prabhu <roprabhu@...co.com>
>> Signed-off-by: Christian Benvenuti <benve@...co.com>
>> Signed-off-by: David Wang <dwang2@...co.com>
> 
> Looks ok to me in principle, but
> 
>> +               /* XXX: If broadcast address present, set IFF_BROADCAST */
>> +               /* XXX: If multicast address present, set IFF_MULTICAST */
>> +               flags |= (tf.flags & TUN_FLT_ALLMULTI ? IFF_ALLMULTI : 0) |
>> +                        (!tf.count ? IFF_PROMISC : 0);
>> +               ret = 0;
>> +               if (tf.count > 0) {
>> +                       alen = ETH_ALEN * tf.count;
>> +                       addrs = kmalloc(alen, GFP_KERNEL);
>> +                       if (!addrs) {
>> +                               dev_put(vlan->dev);
>> +                               return -ENOMEM;
>> +                       }
> 
> I think you need to check tf.count for a maximum value. In theory, a user
> could pass a rather large number (65536) which is not good.

Good point. Will fix it.

> 
> Also the TUNSETTXFILTER code looks sufficiently large that it would be
> better to put it into a separate function. Use "goto" statements in
> order to do the error handling in there, instead of repeating
> lots of kfree and dev_put calls in each error case.

Ok sounds good. Will fix this when I respin the patches.

Thanks for the comments.
Roopa

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