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

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

[Zhang Chen]

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) {
-        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

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

[Jason Wang]

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
>

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

[Zhang, Chen]

> -----Original Message-----
> From: Jason Wang <jasowang@redhat.com>
> Sent: Friday, August 5, 2022 11:46 AM
> To: Zhang, Chen <chen.zhang@intel.com>
> Cc: Peter Maydell <peter.maydell@linaro.org>; Li Zhijian
> <lizhijian@fujitsu.com>; qemu-dev <qemu-devel@nongnu.org>
> Subject: Re: [PATCH] net/colo.c: Fix the pointer issuse reported by Coverity.
> 
> 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().

Yes, you are right. I just checked it for hint of bugs.
Do you think no need to do it?

Thanks
Chen

> 
> 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
> >

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

[Peter Maydell]

On Fri, 5 Aug 2022 at 06:56, Zhang, Chen <chen.zhang@intel.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Jason Wang <jasowang@redhat.com>
> > 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().
>
> Yes, you are right. I just checked it for hint of bugs.
> Do you think no need to do it?

If you think it is a "should never happen unless QEMU is buggy" case, then
 assert(data).

thanks
-- PMM

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

[Zhang, Chen]

> -----Original Message-----
> From: Peter Maydell <peter.maydell@linaro.org>
> Sent: Friday, August 5, 2022 4:53 PM
> To: Zhang, Chen <chen.zhang@intel.com>
> Cc: Jason Wang <jasowang@redhat.com>; Li Zhijian <lizhijian@fujitsu.com>;
> qemu-dev <qemu-devel@nongnu.org>
> Subject: Re: [PATCH] net/colo.c: Fix the pointer issuse reported by Coverity.
> 
> On Fri, 5 Aug 2022 at 06:56, Zhang, Chen <chen.zhang@intel.com> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: Jason Wang <jasowang@redhat.com> 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().
> >
> > Yes, you are right. I just checked it for hint of bugs.
> > Do you think no need to do it?
> 
> If you think it is a "should never happen unless QEMU is buggy" case, then
> assert(data).

OK, I will change it to assert() in V2.

Thanks
Chen

> 
> thanks
> -- PMM