> -----Original Message-----
> From: Jason Wang <jasow...@redhat.com>
> Sent: Tuesday, August 9, 2022 4:12 PM
> To: Zhang, Chen <chen.zh...@intel.com>
> Cc: Peter Maydell <peter.mayd...@linaro.org>; Li Zhijian
> <lizhij...@fujitsu.com>; qemu-dev <qemu-devel@nongnu.org>
> Subject: Re: [PATCH V3] net/colo.c: Fix the pointer issue reported by
> Coverity.
>
> On Tue, Aug 9, 2022 at 11:05 AM Zhang Chen <chen.zh...@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.zh...@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..4f1b4a61f6 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)) ||
>
> Virtio-net starts to support RSS so it means the vnet_hdr size could be
> greater
> than virtio_net_hdr now.
>
> Or did you actually mean "<" here?
No, I just try to avoid overflow with a maliciously over-large
vnet_hdr_len value as Peter's comments.
If enabled the RSS, how to get the maximum of vnet_hdr size?
Thanks
Chen
>
> Thanks
>
> > + (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;
> > }
> > - 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
> >
