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From: Stephen Hemminger <stephen@networkplumber.org>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
Cc: "Morten Brørup" <mb@smartsharesystems.com>,
	dpdk-dev <dev@dpdk.org>, "Jerin Jacob" <jerinj@marvell.com>
Subject: Re: [dpdk-dev] packet data access bug in bpf and pdump libs
Date: Wed, 9 Oct 2019 08:02:18 -0700	[thread overview]
Message-ID: <20191009080218.3711bef3@hermes.lan> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB977258019197431F@irsmsx105.ger.corp.intel.com>

On Wed, 9 Oct 2019 11:11:46 +0000
"Ananyev, Konstantin" <konstantin.ananyev@intel.com> wrote:

> Hi Morten,
> 
> > 
> > Hi Konstantin and Stephen,
> > 
> > I just noticed the same bug in your bpf and pcap libraries:
> > 
> > You are using rte_pktmbuf_mtod(), but should be using rte_pktmbuf_read(). Otherwise you cannot read data across multiple segments.  
> 
> In plain data buffer mode expected input for BPF program is start of first segment packet data.
> Other segments are simply not available to BPF program in that mode.
> AFAIK, cBPF uses the same model.
> 
> > 
> > 
> > Med venlig hilsen / kind regards
> > - Morten Brørup  
> 

For packet capture, the BPF program is only allowed to look at first segment.
pktmbuf_read is expensive and can cause a copy.

  parent reply	other threads:[~2019-10-09 15:02 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-09 11:03 [dpdk-dev] packet data access bug in bpf and pdump libs Morten Brørup
2019-10-09 11:11 ` Ananyev, Konstantin
2019-10-09 11:35   ` Morten Brørup
2019-10-09 15:02   ` Stephen Hemminger [this message]
2019-10-09 15:06     ` Morten Brørup
2019-10-09 15:14       ` Stephen Hemminger
2019-10-09 15:20         ` Morten Brørup
2019-10-09 17:24           ` Stephen Hemminger
2019-10-10  7:29             ` Morten Brørup
2019-10-10 15:36               ` Ananyev, Konstantin
2019-10-11  8:01                 ` Morten Brørup

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