Re: [PATCH V4 RESEND] net/colo.c: Fix the pointer issue reported by Coverity.

[Jason Wang]

On Wed, Aug 17, 2022 at 3:45 PM Zhang, Chen <chen.zhang@intel.com> wrote:
>
> Ping....  Jason and Peter, any comments for this patch?
>
> Thanks
> Chen
>
> > -----Original Message-----
> > From: Zhang, Chen <chen.zhang@intel.com>
> > Sent: Tuesday, August 9, 2022 4:49 PM
> > To: Jason Wang <jasowang@redhat.com>; Peter Maydell
> > <peter.maydell@linaro.org>; Li Zhijian <lizhijian@fujitsu.com>; qemu-dev
> > <qemu-devel@nongnu.org>
> > Cc: Zhang, Chen <chen.zhang@intel.com>
> > Subject: [PATCH V4 RESEND] net/colo.c: Fix the pointer issue reported by
> > Coverity.
> >
> > 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 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 | 18 ++++++++++--------
> >  net/colo.h |  1 +
> >  2 files changed, 11 insertions(+), 8 deletions(-)
> >
> > diff --git a/net/colo.c b/net/colo.c
> > index 6b0ff562ad..2b5568fff4 100644
> > --- a/net/colo.c
> > +++ b/net/colo.c
> > @@ -44,21 +44,23 @@ 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, "
> > +    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)) {
> > +        trace_colo_proxy_main_vnet_info("This packet may be load wrong "
> >                                          "pkt->vnet_hdr_len", 
> > pkt->vnet_hdr_len);

Nit: I think we need to be verbose here, e.g put the pkt_size here at least.

Thanks

> >          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
> >
> > --
> > 2.25.1
>