Re: [PATCH V5] net/colo.c: Fix the pointer issue reported by Coverity.

[Jason Wang]

On Mon, Aug 22, 2022 at 4:29 PM Zhang Chen <chen.zhang@intel.com> wrote:
>
> When enabled 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 needs 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>

Not sure it's worth 7.1. So I queued this for 7.2.

Thanks

> ---
>  net/colo.c       | 25 ++++++++++++++++---------
>  net/colo.h       |  1 +
>  net/trace-events |  2 +-
>  3 files changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/net/colo.c b/net/colo.c
> index 6b0ff562ad..fb2c36a026 100644
> --- a/net/colo.c
> +++ b/net/colo.c
> @@ -44,21 +44,28 @@ 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) {
> -        trace_colo_proxy_main_vnet_info("This packet is not parsed 
> correctly, "
> -                                        "pkt->vnet_hdr_len", 
> pkt->vnet_hdr_len);
> +    assert(data);
> +
> +    /* Check the received vnet_hdr_len then add the offset */
> +    if ((pkt->vnet_hdr_len > sizeof(struct virtio_net_hdr_v1_hash)) ||
> +        (pkt->size < sizeof(struct eth_header) + sizeof(struct vlan_header) +
> +        pkt->vnet_hdr_len)) {
> +        /*
> +         * The received remote packet maybe misconfiguration here,
> +         * Please enable/disable filter module's the vnet_hdr flag at
> +         * the same time.
> +         */
> +        trace_colo_proxy_main_vnet_info("This received packet load wrong ",
> +                                        pkt->vnet_hdr_len, pkt->size);
>          return 1;
>      }
> -    l2hdr_len = eth_get_l2_hdr_length(data);
> +    data += pkt->vnet_hdr_len;
>
> -    if (pkt->size < ETH_HLEN + pkt->vnet_hdr_len) {
> -        trace_colo_proxy_main("pkt->size < ETH_HLEN");
> -        return 1;
> -    }
> +    l2hdr_len = eth_get_l2_hdr_length(data);
>
>      /*
>       * TODO: support vlan.
> diff --git a/net/colo.h b/net/colo.h
> index 8b3e8d5a83..22fc3031f7 100644
> --- a/net/colo.h
> +++ b/net/colo.h
> @@ -18,6 +18,7 @@
>  #include "qemu/jhash.h"
>  #include "qemu/timer.h"
>  #include "net/eth.h"
> +#include "standard-headers/linux/virtio_net.h"
>
>  #define HASHTABLE_MAX_SIZE 16384
>
> diff --git a/net/trace-events b/net/trace-events
> index 6af927b4b9..823a071bdc 100644
> --- a/net/trace-events
> +++ b/net/trace-events
> @@ -9,7 +9,7 @@ vhost_user_event(const char *chr, int event) "chr: %s got 
> event: %d"
>
>  # colo.c
>  colo_proxy_main(const char *chr) ": %s"
> -colo_proxy_main_vnet_info(const char *sta, int size) ": %s = %d"
> +colo_proxy_main_vnet_info(const char *sta, uint32_t vnet_hdr, int size) ": 
> %s pkt->vnet_hdr_len = %u, pkt->size = %d"
>
>  # colo-compare.c
>  colo_compare_main(const char *chr) ": %s"
> --
> 2.25.1
>