linux-kernel - Re: [PATCH 1/1] net: netlink: Fix multicast group storage allocation for families with more than one groups

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Date:	Wed, 13 Jan 2016 09:53:30 +0200
From:	Matti Vaittinen <matti.vaittinen@...ia.com>
To:	EXT David Miller <davem@...emloft.net>
Cc:	johannes.berg@...el.com, jbenc@...hat.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, alexander.sverdlin@...ia.com,
	teppo.o.pennanen@...ia.com
Subject: Re: [PATCH 1/1] net: netlink: Fix multicast group storage allocation
 for families with more than one groups

Hello David & others,

On Tue, Jan 12, 2016 at 04:42:11PM -0500, EXT David Miller wrote:
> But I think your change has an off-by-one bug:
> 
> From: Matti Vaittinen <matti.vaittinen@...ia.com>
> > -		if (id >= mc_groups_longs * BITS_PER_LONG) {
> > +		if (id + n_groups >= mc_groups_longs * BITS_PER_LONG) {
> 
> I think this needs to be "id + n_groups > ".  Consider the existing,
> working, case of "n_groups == 1".  Now you're adding '1' and therefore
> the test needs to be adjusted from >= to >.

Absolutely. I did patch v2.

Br.
    Matti Vaittinen