linux-kernel - Re: [PATCH] flow disector: check if arp

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Message-ID: <1484332575.13165.48.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Fri, 13 Jan 2017 10:36:15 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Colin Ian King <colin.king@...onical.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Alexander Duyck <aduyck@...antis.com>,
        Jiri Pirko <jiri@...lanox.com>,
        Tom Herbert <tom@...bertland.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Simon Horman <simon.horman@...ronome.com>,
        Hadar Hen Zion <hadarh@...lanox.com>,
        Gao Feng <fgao@...ai8.com>, Amir Vadai <amir@...ai.me>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] flow disector: check if arp_eth is null rather than arp

On Fri, 2017-01-13 at 18:25 +0000, Colin Ian King wrote:
> On 13/01/17 18:24, Eric Dumazet wrote:

> > It looks that we try very hard to add critical bugs in flow dissector.
> > 
> > This is embarrassing really.
> > 
> > I am questioning if the __skb_header_pointer() is correct
> > 
> > Why using hlen - sizeof(_arp) ?
> > 
> >                arp_eth = __skb_header_pointer(skb, nhoff + sizeof(_arp),
> >                                               sizeof(_arp_eth), data,
> >                                               hlen - sizeof(_arp),
> >                                               &_arp_eth);
> > 
> 
> Yep, the sizeof maybe dubious too, I overlooked that one; if somebody
> can clarify that then I'll send a V2 if it needs fixing up too.

I am pretty sure we should use hlen instead of (hlen - sizeof(_arp))

A V2 would be nice ;)