[dpdk-stable] [PATCH] vhost: fix IPv4 csum calculation

[Maxime Coquelin]

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 at dpdk.org

Also adding stable in Cc.


> Signed-off-by: Flavio Leitner <fbl at 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 at redhat.com>

I'll add the Fixes tag while applying.

Thanks!
Maxime