| Message ID | 20220805093813.119839-1-chen.zhang@intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | [V2] net/colo.c: Fix the pointer issuse reported by Coverity. | expand |
> -----Original Message----- > From: Peter Maydell <peter.maydell@linaro.org> > Sent: Friday, August 5, 2022 5:57 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 V2] net/colo.c: Fix the pointer issuse reported by > Coverity. > > On Fri, 5 Aug 2022 at 10:53, 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 | 17 +++++++++-------- > > 1 file changed, 9 insertions(+), 8 deletions(-) > > > > diff --git a/net/colo.c b/net/colo.c > > index 6b0ff562ad..524afa3d9b 100644 > > --- a/net/colo.c > > +++ b/net/colo.c > > @@ -44,21 +44,22 @@ 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->size < sizeof(struct eth_header) + sizeof(struct vlan_header) > > + + pkt->vnet_hdr_len) { > > I think this expression needs more care to avoid overflow with a maliciously > over-large vnet_hdr_len value. > > Casting pkt->vnet_hdr_len to int64_t would be one way to do that; there > may be better approaches. Yes, you are right. And I found better to use this check to avoid overflow: "pkt->vnet_hdr_len < sizeof(struct virtio_net_hdr)" I will fix it in next version. Thanks Chen > > thanks > -- PMM
diff --git a/net/colo.c b/net/colo.c index 6b0ff562ad..524afa3d9b 100644 --- a/net/colo.c +++ b/net/colo.c @@ -44,21 +44,22 @@ 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->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.
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 | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)