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

[Arnd Bergmann <arnd@arndb.de>]

On Wednesday 07 September 2011, Roopa Prabhu wrote:
> From: Roopa Prabhu <roprabhu@cisco.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@cisco.com>
> Signed-off-by: Christian Benvenuti <benve@cisco.com>
> Signed-off-by: David Wang <dwang2@cisco.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.

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.

	Arnd