[PATCH v2] gro : check for payload length after the trim

[Kumara Parameshwaran]

From: Kumara Parameshwaran <kumaraparamesh92 at gmail.com>

When packet is padded with extra bytes the
the validation of the payload length should be done
after the trim operation

Fixes: b8a55871d5af ("gro: trim tail padding bytes")
Cc: stable at dpdk.org

Signed-off-by: Kumara Parameshwaran <kumaraparamesh92 at gmail.com>
---
v1:
	If there is padding to the ethernet frame cases where timestamp is disabled
	the packet length should be validated with the total ip length as packet length 
	is used in the GRO merging logic

v2:
	Trim the packet length and then check for the protocol payload validation
 lib/gro/gro_tcp4.c | 11 ++++++-----
 lib/gro/gro_udp4.c | 10 +++++-----
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c
index 8f5e800250..0014096e63 100644
--- a/lib/gro/gro_tcp4.c
+++ b/lib/gro/gro_tcp4.c
@@ -225,6 +225,12 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
 	 */
 	if (tcp_hdr->tcp_flags != RTE_TCP_ACK_FLAG)
 		return -1;
+
+	/* trim the tail padding bytes */
+	ip_tlen = rte_be_to_cpu_16(ipv4_hdr->total_length);
+	if (pkt->pkt_len > (uint32_t)(ip_tlen + pkt->l2_len))
+		rte_pktmbuf_trim(pkt, pkt->pkt_len - ip_tlen - pkt->l2_len);
+
 	/*
 	 * Don't process the packet whose payload length is less than or
 	 * equal to 0.
@@ -233,11 +239,6 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
 	if (tcp_dl <= 0)
 		return -1;
 
-	/* trim the tail padding bytes */
-	ip_tlen = rte_be_to_cpu_16(ipv4_hdr->total_length);
-	if (pkt->pkt_len > (uint32_t)(ip_tlen + pkt->l2_len))
-		rte_pktmbuf_trim(pkt, pkt->pkt_len - ip_tlen - pkt->l2_len);
-
 	/*
 	 * Save IPv4 ID for the packet whose DF bit is 0. For the packet
 	 * whose DF bit is 1, IPv4 ID is ignored.
diff --git a/lib/gro/gro_udp4.c b/lib/gro/gro_udp4.c
index 839f9748b7..42596d33b6 100644
--- a/lib/gro/gro_udp4.c
+++ b/lib/gro/gro_udp4.c
@@ -220,6 +220,11 @@ gro_udp4_reassemble(struct rte_mbuf *pkt,
 	if (!is_ipv4_fragment(ipv4_hdr))
 		return -1;
 
+	ip_dl = rte_be_to_cpu_16(ipv4_hdr->total_length);
+	/* trim the tail padding bytes */
+	if (pkt->pkt_len > (uint32_t)(ip_dl + pkt->l2_len))
+		rte_pktmbuf_trim(pkt, pkt->pkt_len - ip_dl - pkt->l2_len);
+
 	/*
 	 * Don't process the packet whose payload length is less than or
 	 * equal to 0.
@@ -227,14 +232,9 @@ gro_udp4_reassemble(struct rte_mbuf *pkt,
 	if (pkt->pkt_len <= hdr_len)
 		return -1;
 
-	ip_dl = rte_be_to_cpu_16(ipv4_hdr->total_length);
 	if (ip_dl <= pkt->l3_len)
 		return -1;
 
-	/* trim the tail padding bytes */
-	if (pkt->pkt_len > (uint32_t)(ip_dl + pkt->l2_len))
-		rte_pktmbuf_trim(pkt, pkt->pkt_len - ip_dl - pkt->l2_len);
-
 	ip_dl -= pkt->l3_len;
 	ip_id = rte_be_to_cpu_16(ipv4_hdr->packet_id);
 	frag_offset = rte_be_to_cpu_16(ipv4_hdr->fragment_offset);
-- 
2.25.1