linux-kernel - Re: [PATCH] bridge: don't try to update timers in case of broken MLD queries

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Message-ID: <20130805154222.58361734@nehalam.linuxnetplumber.net>
Date:	Mon, 5 Aug 2013 15:42:22 -0700
From:	Stephen Hemminger <stephen@...workplumber.org>
To:	Linus Lüssing <linus.luessing@....de>
Cc:	bridge@...ts.linux-foundation.org,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Cong Wang <amwang@...hat.com>,
	Adam Baker <linux@...er-net.org.uk>,
	Paul Bolle <pebolle@...cali.nl>
Subject: Re: [PATCH] bridge: don't try to update timers in case of broken
 MLD queries

On Tue,  6 Aug 2013 00:32:05 +0200
Linus Lüssing <linus.luessing@....de> wrote:

> Currently we are reading an uninitialized value for the max_delay
> variable when snooping an MLD query message of invalid length and would
> update our timers with that.
> 
> Fixing this by simply ignoring such broken MLD queries (just like we do
> for IGMP already).
> 
> This is a regression introduced by:
> "bridge: disable snooping if there is no querier" (b00589af3b04)
> 
> Reported-by: Paul Bolle <pebolle@...cali.nl>
> Signed-off-by: Linus Lüssing <linus.luessing@....de>
> ---
>  net/bridge/br_multicast.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> index 61c5e81..08e576a 100644
> --- a/net/bridge/br_multicast.c
> +++ b/net/bridge/br_multicast.c
> @@ -1195,7 +1195,7 @@ static int br_ip6_multicast_query(struct net_bridge *br,
>  		max_delay = msecs_to_jiffies(ntohs(mld->mld_maxdelay));
>  		if (max_delay)
>  			group = &mld->mld_mca;
> -	} else if (skb->len >= sizeof(*mld2q)) {
> +	} else {
>  		if (!pskb_may_pull(skb, sizeof(*mld2q))) {
>  			err = -EINVAL;
>  			goto out;

Why not use else if here, other than that looks great.
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