[ovs-dev] [patch v1] conntrack: Fix 'reverse_nat_packet()' variable datatype.

[Darrell Ball]

The datatype 'pad' in the function 'reverse_nat_packet()' was incorrectly
declared as 'char' instead of 'uint8_t'. This can affect reverse natting
of icmpX packets with padding > 127 bytes.  At the same time, add some
comments regarding 'extract_l3_ipvX' usage in this function.  Found by
inspection.

Fixes: edd1bef468c0 ("dpdk: Add more ICMP Related NAT support.")
Signed-off-by: Darrell Ball <dlu998 at gmail.com>
---
 lib/conntrack.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/conntrack.c b/lib/conntrack.c
index e5266e5..79d2711 100644
--- a/lib/conntrack.c
+++ b/lib/conntrack.c
@@ -688,7 +688,7 @@ static void
 reverse_nat_packet(struct dp_packet *pkt, const struct conn *conn)
 {
     char *tail = dp_packet_tail(pkt);
-    char pad = dp_packet_l2_pad_size(pkt);
+    uint8_t pad = dp_packet_l2_pad_size(pkt);
     struct conn_key inner_key;
     const char *inner_l4 = NULL;
     uint16_t orig_l3_ofs = pkt->l3_ofs;
@@ -698,6 +698,7 @@ reverse_nat_packet(struct dp_packet *pkt, const struct conn *conn)
         struct ip_header *nh = dp_packet_l3(pkt);
         struct icmp_header *icmp = dp_packet_l4(pkt);
         struct ip_header *inner_l3 = (struct ip_header *) (icmp + 1);
+        /* conn_key_extract() usage already verified extraction success. */
         extract_l3_ipv4(&inner_key, inner_l3, tail - ((char *)inner_l3) - pad,
                         &inner_l4, false);
         pkt->l3_ofs += (char *) inner_l3 - (char *) nh;
@@ -719,6 +720,7 @@ reverse_nat_packet(struct dp_packet *pkt, const struct conn *conn)
         struct icmp6_error_header *icmp6 = dp_packet_l4(pkt);
         struct ovs_16aligned_ip6_hdr *inner_l3_6 =
             (struct ovs_16aligned_ip6_hdr *) (icmp6 + 1);
+        /* conn_key_extract() usage already verified extraction success. */
         extract_l3_ipv6(&inner_key, inner_l3_6,
                         tail - ((char *)inner_l3_6) - pad,
                         &inner_l4);
-- 
1.9.1