Re: [dpdk-dev] [PATCH] vhost: fix IPv4 csum calculation

[Flavio Leitner <fbl@sysclose.org>]

On Thu, 24 Oct 2019 16:32:43 +0200
Maxime Coquelin <maxime.coquelin@redhat.com> wrote:

> Hi Flavio,
> 
> On 10/24/19 4:28 PM, Flavio Leitner wrote:
> > Currently the IPv4 header checksum is calculated including its
> > current value, which can be a valid checksum or just garbage.
> > In any case, if the original value is not zero, then the result
> > is always wrong.
> > 
> > The IPv4 checksum is defined in RFC791, page 14 says:
> >   Header Checksum:  16 bits
> > 
> >   The checksum algorithm is:
> >   The checksum field is the 16 bit one's complement of the one's
> >   complement sum of all 16 bit words in the header.  For purposes of
> >   computing the checksum, the value of the checksum field is zero.
> > 
> > Thus force the csum field to always be zero.  
> 
> I think we need Fixes tag:
> 
> Fixes: b08b8cfeb2ae ("vhost: fix IP checksum")
> Cc: stable@dpdk.org
> 
> Also adding stable in Cc.
> 
> 
> > Signed-off-by: Flavio Leitner <fbl@sysclose.org>
> > ---
> >  lib/librte_vhost/virtio_net.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/lib/librte_vhost/virtio_net.c
> > b/lib/librte_vhost/virtio_net.c index eae7825f04..cde7498c76 100644
> > --- a/lib/librte_vhost/virtio_net.c
> > +++ b/lib/librte_vhost/virtio_net.c
> > @@ -445,6 +445,7 @@ virtio_enqueue_offload(struct rte_mbuf *m_buf,
> > struct virtio_net_hdr *net_hdr) 
> >  		ipv4_hdr = rte_pktmbuf_mtod_offset(m_buf, struct
> > rte_ipv4_hdr *, m_buf->l2_len);
> > +		ipv4_hdr->hdr_checksum = 0;
> >  		ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
> >  	}
> >  
> >   
> 
> Other than that:
> 
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> 
> I'll add the Fixes tag while applying.

Not sure if you will send to stable, so I did v2 just in case.
Feel free to drop either one if you took care of those items already.
Thanks!
fbl