netdev - RE: [PATCH 1/1 V3] bridge: fix br_multicast_ipv6

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Message-ID: <6F5C1D715B2DA5498A628E6B9C124F04019BF9E404@hasmsx504.ger.corp.intel.com>
Date:	Mon, 3 Jan 2011 11:43:52 +0200
From:	"Winkler, Tomas" <tomas.winkler@...el.com>
To:	Johannes Berg <johannes@...solutions.net>
CC:	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Stephen Hemminger <shemminger@...tta.com>
Subject: RE: [PATCH 1/1 V3] bridge: fix br_multicast_ipv6_rcv for paged skbs



> -----Original Message-----
> From: Johannes Berg [mailto:johannes@...solutions.net]
> Sent: Monday, January 03, 2011 11:34 AM
> To: Winkler, Tomas
> Cc: davem@...emloft.net; netdev@...r.kernel.org; Stephen Hemminger
> Subject: Re: [PATCH 1/1 V3] bridge: fix br_multicast_ipv6_rcv for paged skbs
> 
> On Sun, 2011-01-02 at 22:18 +0200, Tomas Winkler wrote:
> 
> >  	icmp6h = icmp6_hdr(skb2);
> >
> >  	switch (icmp6h->icmp6_type) {
> > @@ -1516,7 +1517,12 @@ static int br_multicast_ipv6_rcv(struct net_bridge
> *br,
> >  	switch (icmp6h->icmp6_type) {
> >  	case ICMPV6_MGM_REPORT:
> >  	    {
> > -		struct mld_msg *mld = (struct mld_msg *)icmp6h;
> > +		struct mld_msg *mld;
> > +		if (!pskb_may_pull(skb2, sizeof(*mld))) {
> > +			err = -EINVAL;
> > +			goto out;
> > +		}
> > +		mld = (struct mld_msg *)icmp6h;
> 
> This (and the second instance) is incorrect afaict -- the pointer
> "icmp6h" should be reloaded after the pskb_may_pull(), no?

mld_msg is bigger than icmp6h by sizeof(in6_addr) so we have to try pull again a bigger chunk. 

> 
> Also, the "out_nopush" thing is pointless since the push is completely
> unnecessary as "skb2 != skb" is always true.

You are right if skb_clone doesn't return the same pointer then yes. Shame, but I'm not a sbk expert. I'm diving into it now.

Thanks
Tomas
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