pinctrl: Fix icmp6 packet corruption issue

The commit f792b1a("Fix ACL reject action for UDP packets.")
didn't updated the 'struct ip6_hdr' pointer after calling
dp_packet_put(), as dp_packet_put() can reallocate memory making the
old references to packet pointers invalid.

This patch fixes this issue.

Fixes: f792b1a("Fix ACL reject action for UDP packets.")
Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=1834655
Acked-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Numan Siddique <numans@ovn.org>

controller/pinctrl.c

@@ -1570,8 +1570,6 @@ pinctrl_handle_icmp(struct rconn *swconn, const struct flow *ip_flow,
         }
         ih->icmp6_base.icmp6_cksum = 0;
 
-        nh = dp_packet_l3(&packet);
-
         /* RFC 4443: 3.1.
          *
          * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
@@ -1594,9 +1592,11 @@ pinctrl_handle_icmp(struct rconn *swconn, const struct flow *ip_flow,
         }
 
         dp_packet_put(&packet, in_ip, in_ip_len);
+        nh = dp_packet_l3(&packet);
         nh->ip6_plen = htons(ICMP6_DATA_HEADER_LEN + in_ip_len);
 
         icmpv6_csum = packet_csum_pseudoheader6(dp_packet_l3(&packet));
+        ih = dp_packet_l4(&packet);
         ih->icmp6_base.icmp6_cksum = csum_finish(
             csum_continue(icmpv6_csum, ih,
                           in_ip_len + ICMP6_DATA_HEADER_LEN));

tests/system-ovn.at

@@ -3967,7 +3967,7 @@ OVS_WAIT_UNTIL([
 NS_CHECK_EXEC([sw0-p1-rej], [tcpdump -n -c 1 -i sw0-p1-rej udp port 90 > sw0-p1-rej-udp.pcap &], [0])
 NS_CHECK_EXEC([sw0-p1-rej], [tcpdump -n -c 1 -i sw0-p1-rej icmp > sw0-p1-rej-icmp.pcap &], [0])
 
-echo "foo" > foo
+printf '.%.0s' {1..100} > foo
 OVS_WAIT_UNTIL([
     ip netns exec sw0-p1-rej nc -u 10.0.0.4 90 < foo
     c=$(cat sw0-p1-rej-icmp.pcap | grep \