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Re: [PATCH] net/colo.c: Fix the pointer issuse reported by Coverity.


From: Jason Wang
Subject: Re: [PATCH] net/colo.c: Fix the pointer issuse reported by Coverity.
Date: Fri, 5 Aug 2022 11:46:13 +0800

On Tue, Aug 2, 2022 at 4:24 PM Zhang Chen <chen.zhang@intel.com> wrote:
>
> When enable the virtio-net-pci, guest network packet will
> load the vnet_hdr. In COLO status, the primary VM's network
> packet maybe redirect to another VM, it need filter-redirect
> enable the vnet_hdr flag at the same time, COLO-proxy will
> correctly parse the original network packet. If have any
> misconfiguration here, the vnet_hdr_len is wrong for parse
> the packet, the data+offset will point to wrong place.
>
> Signed-off-by: Zhang Chen <chen.zhang@intel.com>
> ---
>  net/colo.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/net/colo.c b/net/colo.c
> index 6b0ff562ad..dfb15b4c14 100644
> --- a/net/colo.c
> +++ b/net/colo.c
> @@ -44,21 +44,25 @@ int parse_packet_early(Packet *pkt)
>  {
>      int network_length;
>      static const uint8_t vlan[] = {0x81, 0x00};
> -    uint8_t *data = pkt->data + pkt->vnet_hdr_len;
> +    uint8_t *data = pkt->data;
>      uint16_t l3_proto;
>      ssize_t l2hdr_len;
>
>      if (data == NULL) {

I wonder under which case we can see data == NULL?

AFAIK, data is either dup via packet_new() or assigned to a pointer to
the buf in packet_new_nocopy().

Thanks

> -        trace_colo_proxy_main_vnet_info("This packet is not parsed 
> correctly, "
> -                                        "pkt->vnet_hdr_len", 
> pkt->vnet_hdr_len);
> +        trace_colo_proxy_main("COLO-proxy got NULL data packet ");
>          return 1;
>      }
> -    l2hdr_len = eth_get_l2_hdr_length(data);
>
> -    if (pkt->size < ETH_HLEN + pkt->vnet_hdr_len) {
> -        trace_colo_proxy_main("pkt->size < ETH_HLEN");
> +    /* Check the received vnet_hdr_len then add the offset */
> +    if (pkt->size < sizeof(struct eth_header) + sizeof(struct vlan_header)
> +        + pkt->vnet_hdr_len) {
> +        trace_colo_proxy_main_vnet_info("This packet may be load wrong "
> +                                        "pkt->vnet_hdr_len", 
> pkt->vnet_hdr_len);
>          return 1;
>      }
> +    data += pkt->vnet_hdr_len;
> +
> +    l2hdr_len = eth_get_l2_hdr_length(data);
>
>      /*
>       * TODO: support vlan.
> --
> 2.25.1
>




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