netdev - Re: suspicius csum initialization in vmxnet3_rx

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Message-ID: <20180601221243.GA25617@neilslaptop.think-freely.org>
Date:   Fri, 1 Jun 2018 18:12:43 -0400
From:   Neil Horman <nhorman@...driver.com>
To:     Ronak Doshi <doshir@...are.com>
Cc:     Paolo Abeni <pabeni@...hat.com>, Guolin Yang <gyang@...are.com>,
        Boon Ang <bang@...are.com>, Louis Luo <llouis@...are.com>,
        netdev@...r.kernel.org
Subject: Re: suspicius csum initialization in vmxnet3_rx_csum

On Fri, Jun 01, 2018 at 11:10:01AM -0700, Ronak Doshi wrote:
> 
> 
> On Thu, 31 May 2018, Neil Horman wrote:
> 
> > On Thu, May 31, 2018 at 11:02:34AM -0700, Ronak Doshi wrote:
> > > 
> > > On Wed, 30 May 2018, Paolo Abeni wrote:
> > > 
> > > > Hi,
> > > > 
> > > > On Thu, 2018-05-24 at 21:48 +0000, Guolin Yang wrote:
> > > > > Yes, that code  is not correct, we should fix that code
> > > > 
> > > > Did you have any chance to address the issue and/or to give a more in-
> > > > deepth look to the change proposed in my initial email?
> > > >  
> > > Hi Paolo,
> > > 
> > > Can you provide the esx build you are using? It can be found using 
> > > "vmware -vl" on ESX host.
> > > 
> > > Did you try your proposed fix and did it work? Are you sure the packet
> > > hits the below if block and not the else block? I still don't think the
> > > ICMP packet will go through the below if block.
> > > 
> > >    if (gdesc->rcd.csum) {
> > > 	skb->csum = htons(gdesc->rcd.csum);
> > > 	skb->ip_summed = CHECKSUM_PARTIAL;
> > >    } else {
> > > 	skb_checksum_none_assert(skb);
> > >    }
> > > 
> > > The vmxnet3 emulation does not calculate rcd.csum for ICMP packet and
> > > hence should go through the else block i.e. checksum none.
> > > 
> > What packet types will rcd.csum be set for?
> > Neil 
> > 
> I looked thorugh the emulation code and found that rcd.csum is not set. 
> For valid v4/v6, TCP/UDP packets the code block above the mentioend "if" 
> block will be executed or else it will go through checksum none.
> 
> That's why I wanted to know (in previous emails) which ESX build is being 
> used while this was tested. The code block under "if (gdesc->rcd.csum)" 
> block might seem incorrect but it shouldn't be hit as rcd.csum is not set. 
> Hence, I asked did the fix provided by Paolo worked for the icmp test?
> 
Paolo will have to tell you that specifically I'm afraid.  I'm not sure if the patch was tested or not.
> Thanks,
> Ronak
>