[PATCH v4] lib/net: fix tcp/udp cksum with padding data

[Kaiwen Deng <kaiwenx.deng@intel.com>]

IEEE 802 packets may have a minimum size limit. The data fields
should be padded when necessary. In some cases, the padding data
is not zero.

In 'rte_ipv4_udptcp_cksum_mbuf()', as payload length
"mbuf->pkt_len - l4_off" is used, which includes padding and if
padding is not zero it will end up producing wrong checksum.

This patch will use IP header to get the payload size to calculate
tcp/udp checksum.

Fixes: d178f693bbfe ("net: add UDP/TCP checksum in mbuf segments")
Cc: stable@dpdk.org

Signed-off-by: Kaiwen Deng <kaiwenx.deng@intel.com>
---
 lib/net/rte_ip.h | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/lib/net/rte_ip.h b/lib/net/rte_ip.h
index 6fa98a5a0f..bcdce723a5 100644
--- a/lib/net/rte_ip.h
+++ b/lib/net/rte_ip.h
@@ -419,11 +419,15 @@ __rte_ipv4_udptcp_cksum_mbuf(const struct rte_mbuf *m,
 {
 	uint16_t raw_cksum;
 	uint32_t cksum;
+	uint16_t len;
 
-	if (l4_off > m->pkt_len)
-		return 0;
+	if (unlikely(l4_off > m->pkt_len))
+		return 0; /* invalid params, return a dummy value */
+
+	len = rte_be_to_cpu_16(ipv4_hdr->total_length) -
+				(uint16_t)rte_ipv4_hdr_len(ipv4_hdr);
 
-	if (rte_raw_cksum_mbuf(m, l4_off, m->pkt_len - l4_off, &raw_cksum))
+	if (rte_raw_cksum_mbuf(m, l4_off, len, &raw_cksum))
 		return 0;
 
 	cksum = raw_cksum + rte_ipv4_phdr_cksum(ipv4_hdr, 0);
@@ -663,10 +667,11 @@ __rte_ipv6_udptcp_cksum_mbuf(const struct rte_mbuf *m,
 	uint16_t raw_cksum;
 	uint32_t cksum;
 
-	if (l4_off > m->pkt_len)
-		return 0;
+	if (unlikely(l4_off > m->pkt_len))
+		return 0; /* invalid params, return a dummy value */
 
-	if (rte_raw_cksum_mbuf(m, l4_off, m->pkt_len - l4_off, &raw_cksum))
+	if (rte_raw_cksum_mbuf(m, l4_off,
+		rte_be_to_cpu_16(ipv6_hdr->payload_len), &raw_cksum))
 		return 0;
 
 	cksum = raw_cksum + rte_ipv6_phdr_cksum(ipv6_hdr, 0);
-- 
2.34.1