[PATCH v3] lib/net: fix tcp/udp cksum with padding data

[Kaiwen Deng]

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 at dpdk.org

Signed-off-by: Kaiwen Deng <kaiwenx.deng at intel.com>
---
 lib/net/rte_ip.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/net/rte_ip.h b/lib/net/rte_ip.h
index 6fa98a5a0f..c503a2b57f 100644
--- a/lib/net/rte_ip.h
+++ b/lib/net/rte_ip.h
@@ -423,7 +423,10 @@ __rte_ipv4_udptcp_cksum_mbuf(const struct rte_mbuf *m,
 	if (l4_off > m->pkt_len)
 		return 0;
 
-	if (rte_raw_cksum_mbuf(m, l4_off, m->pkt_len - l4_off, &raw_cksum))
+	uint16_t 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, len, &raw_cksum))
 		return 0;
 
 	cksum = raw_cksum + rte_ipv4_phdr_cksum(ipv4_hdr, 0);
@@ -666,7 +669,9 @@ __rte_ipv6_udptcp_cksum_mbuf(const struct rte_mbuf *m,
 	if (l4_off > m->pkt_len)
 		return 0;
 
-	if (rte_raw_cksum_mbuf(m, l4_off, m->pkt_len - l4_off, &raw_cksum))
+	uint16_t len = rte_be_to_cpu_16(ipv6_hdr->payload_len);
+
+	if (rte_raw_cksum_mbuf(m, l4_off, len, &raw_cksum))
 		return 0;
 
 	cksum = raw_cksum + rte_ipv6_phdr_cksum(ipv6_hdr, 0);
-- 
2.34.1