Re: [PATCH 4/4] net/colo.c: fix segmentation fault when packet is not parsed correctly

["lizhijian@fujitsu.com" <lizhijian@fujitsu.com>]

On 09/03/2022 16:38, Zhang Chen wrote:
> When COLO use only one vnet_hdr_support parameter between
> filter-redirector and filter-mirror(or colo-compare), COLO will crash
> with segmentation fault. Back track as follow:
>
> Thread 1 "qemu-system-x86" received signal SIGSEGV, Segmentation fault.
> 0x0000555555cb200b in eth_get_l2_hdr_length (p=0x0)
>      at /home/tao/project/COLO/colo-qemu/include/net/eth.h:296
> 296         uint16_t proto = be16_to_cpu(PKT_GET_ETH_HDR(p)->h_proto);
> (gdb) bt
> 0  0x0000555555cb200b in eth_get_l2_hdr_length (p=0x0)
>      at /home/tao/project/COLO/colo-qemu/include/net/eth.h:296
> 1  0x0000555555cb22b4 in parse_packet_early (pkt=0x555556a44840) at
> net/colo.c:49
> 2  0x0000555555cb2b91 in is_tcp_packet (pkt=0x555556a44840) at
> net/filter-rewriter.c:63
>
> So wrong vnet_hdr_len will cause pkt->data become NULL.
Not sure if we can check this earlier, well

Reviewed-by: Li Zhijian <lizhijian@fujitsu.com>


> Add check to
> raise error and add trace-events to track vnet_hdr_len.
>
> Signed-off-by: Tao Xu <tao3.xu@intel.com>
> Signed-off-by: Zhang Chen <chen.zhang@intel.com>


> ---
>   net/colo.c       | 9 ++++++++-
>   net/trace-events | 1 +
>   2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/net/colo.c b/net/colo.c
> index 694f3c93ef..6b0ff562ad 100644
> --- a/net/colo.c
> +++ b/net/colo.c
> @@ -46,7 +46,14 @@ int parse_packet_early(Packet *pkt)
>       static const uint8_t vlan[] = {0x81, 0x00};
>       uint8_t *data = pkt->data + pkt->vnet_hdr_len;
>       uint16_t l3_proto;
> -    ssize_t l2hdr_len = eth_get_l2_hdr_length(data);
> +    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);
> +        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");
> diff --git a/net/trace-events b/net/trace-events
> index d7a17256cc..6af927b4b9 100644
> --- a/net/trace-events
> +++ b/net/trace-events
> @@ -9,6 +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-compare.c
>   colo_compare_main(const char *chr) ": %s"