Re: Promiscuity counter underflow

[Daniel Borkmann <danborkmann@xxxxxxxxxxxxxx>]

Hi Emmanuel,

right, since it is checked for overflows, a misuse of this function
the other way round could end in a
mess, too. What do you think David?

2010/5/11 Emmanuel Roullit <emmanuel@xxxxxxxxxxxxxxx>:
> Signed-off-by: Emmanuel Roullit <emmanuel@xxxxxxxxxxxxxxx>
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index f769098..f49dbde 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -3591,6 +3591,13 @@ static int __dev_set_promiscuity(struct net_device *dev, int inc)
>
>        ASSERT_RTNL();
>
> +       if (inc < 0 && -inc > dev->promiscuity) {
> +               printk(KERN_WARNING "%s: promiscuity touches bottom, "
> +                       "set promiscuity failed, promiscuity feature "
> +                       "of device might be broken.\n", dev->name);
> +               return -EOVERFLOW;
> +       }
> +
>        dev->flags |= IFF_PROMISC;
>        dev->promiscuity += inc;
>        if (dev->promiscuity == 0) {

Cheers,
                     Daniel
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