Re: [ovs-dev] [PATCH ovn v2] controller: Fix misaligned access to ip6_hdr

[Mark Michelson]

Thanks for the clarification Ales.

Acked-by: Mark Michelson <mmich...@redhat.com>

On 7/26/22 01:23, Ales Musil wrote:

I forgot to add the v2 comment, so for clarification just the commit title
has changed between the versions.

Thanks,
Ales

On Mon, Jul 25, 2022 at 5:19 PM Ales Musil <amu...@redhat.com> wrote:

The ip6_hdr is aligned to 4 bytes, but the pointer
from dp_packet_l3 is aligned to 2 bytes. Use
ovs_16aligned_ip6_hdr instead to get 2 bytes alignment.

Signed-off-by: Ales Musil <amu...@redhat.com>
---
  controller/pinctrl.c | 12 +++++++-----
  1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/controller/pinctrl.c b/controller/pinctrl.c
index 38e8590af..21c78bed4 100644
--- a/controller/pinctrl.c
+++ b/controller/pinctrl.c
@@ -887,7 +887,9 @@ pinctrl_parse_dhcpv6_reply(struct dp_packet *pkt_in,
      OVS_REQUIRES(pinctrl_mutex)
  {
      struct eth_header *eth = dp_packet_eth(pkt_in);
-    struct ip6_hdr *in_ip = dp_packet_l3(pkt_in);
+    struct ovs_16aligned_ip6_hdr *in_ip = dp_packet_l3(pkt_in);
+    struct in6_addr ip6_src;
+    memcpy(&ip6_src, &in_ip->ip6_src, sizeof ip6_src);
      struct udp_header *udp_in = dp_packet_l4(pkt_in);
      unsigned char *in_dhcpv6_data = (unsigned char *)(udp_in + 1);
      size_t dlen = MIN(ntohs(udp_in->udp_len), dp_packet_l4_size(pkt_in));
@@ -971,7 +973,7 @@ pinctrl_parse_dhcpv6_reply(struct dp_packet *pkt_in,
                          " aid %d", ip6_s, prefix, prefix_len, aid);
          }
          pinctrl_prefixd_state_handler(ip_flow, ipv6, aid, eth->eth_src,
-                                      in_ip->ip6_src, prefix_len, t1, t2,
+                                      ip6_src, prefix_len, t1, t2,
                                        plife_time, vlife_time, uuid,
uuid_len);
      } else if (uuid) {
          free(uuid);
@@ -3736,7 +3738,7 @@ packet_put_ra_rdnss_opt(struct dp_packet *b, uint8_t
num,
                          ovs_be32 lifetime, const struct in6_addr *dns)
  {
      size_t prev_l4_size = dp_packet_l4_size(b);
-    struct ip6_hdr *nh = dp_packet_l3(b);
+    struct ovs_16aligned_ip6_hdr *nh = dp_packet_l3(b);
      size_t len = 2 * num + 1;

      nh->ip6_plen = htons(prev_l4_size + len * 8);
@@ -3771,7 +3773,7 @@ packet_put_ra_dnssl_opt(struct dp_packet *b,
ovs_be32 lifetime,
          return;
      }

-    struct ip6_hdr *nh = dp_packet_l3(b);
+    struct ovs_16aligned_ip6_hdr *nh = dp_packet_l3(b);
      nh->ip6_plen = htons(prev_l4_size + size);

      struct ovs_nd_dnssl *nd_dnssl = dp_packet_put_uninit(b, sizeof
*nd_dnssl);
@@ -3850,7 +3852,7 @@ packet_put_ra_route_info_opt(struct dp_packet *b,
ovs_be32 lifetime,
          }
      }

-    struct ip6_hdr *nh = dp_packet_l3(b);
+    struct ovs_16aligned_ip6_hdr *nh = dp_packet_l3(b);
      nh->ip6_plen = htons(prev_l4_size + size);
      struct ovs_ra_msg *ra = dp_packet_l4(b);
      ra->icmph.icmp6_cksum = 0;
--
2.35.3

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