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

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 10/24/19 6:31 PM, Flavio Leitner wrote:
> 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
> 
> 

I synced with Ferruh, and he proposed to pick it directly for -rc1.

Thanks!
Maxime