netdev - Re: [PATCH net-next 2/2] flow_dissector: add support for dst, hop-by-hop and routing ext hdrs

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Message-ID: <1434159454.27504.101.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Fri, 12 Jun 2015 18:37:34 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:	davem@...emloft.net, Tom Herbert <tom@...bertland.com>,
	edumazet@...gle.com, netdev@...r.kernel.org,
	dan.carpenter@...cle.com
Subject: Re: [PATCH net-next 2/2] flow_dissector: add support for dst,
 hop-by-hop and routing ext hdrs

On Fri, 2015-06-12 at 18:27 -0700, Alexei Starovoitov wrote:
> On Fri, Jun 12, 2015 at 09:01:06AM -0700, Tom Herbert wrote:
> > If dst, hop-by-hop or routing extension headers are present determine
> > length of the options and skip over them in flow dissection.
> > 
> > Signed-off-by: Tom Herbert <tom@...bertland.com>
> > ---
> >  net/core/flow_dissector.c | 17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> > 
> > diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
> > index 1818cdc..22e4dff 100644
> > --- a/net/core/flow_dissector.c
> > +++ b/net/core/flow_dissector.c
> > @@ -327,6 +327,7 @@ mpls:
> >  		return false;
> >  	}
> >  
> > +ip_proto_again:
> >  	switch (ip_proto) {
> >  	case IPPROTO_GRE: {
> >  		struct gre_hdr {
> > @@ -383,6 +384,22 @@ mpls:
> >  		}
> >  		goto again;
> >  	}
> > +	case NEXTHDR_HOP:
> > +	case NEXTHDR_ROUTING:
> > +	case NEXTHDR_DEST: {
> > +		u8 _opthdr[2], *opthdr;
> > +
> > +		if (proto != htons(ETH_P_IPV6))
> > +			break;
> > +
> > +		opthdr = __skb_header_pointer(skb, nhoff, sizeof(_opthdr),
> > +					      data, hlen, &_opthdr);
> > +
> > +		ip_proto = _opthdr[0];
> > +		nhoff += (_opthdr[1] + 1) << 3;
> > +
> > +		goto ip_proto_again;
> > +	}
> 
> Dave,
> 
> please revert it. My server locks up during boot with:

Seems easy to fix instead ?

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 22e4dffa0c8b3b9a20a7324eae1627313e14ce30..476e5dda59e19822dba98a931369ff2666c59c0d 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -394,9 +394,11 @@ ip_proto_again:
 
 		opthdr = __skb_header_pointer(skb, nhoff, sizeof(_opthdr),
 					      data, hlen, &_opthdr);
+		if (!opthdr)
+			return false;
 
-		ip_proto = _opthdr[0];
-		nhoff += (_opthdr[1] + 1) << 3;
+		ip_proto = opthdr[0];
+		nhoff += (opthdr[1] + 1) << 3;
 
 		goto ip_proto_again;
 	}


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