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From: "jiangheng (G)" <jiangheng14@huawei.com>
To: "dev@dpdk.org" <dev@dpdk.org>
Subject: [PATCH] TCP data length is incorrectly calculated in the
 gro_tcp4_reassemble function.
Thread-Topic: [PATCH] TCP data length is incorrectly calculated in the
 gro_tcp4_reassemble function.
Thread-Index: AdjTQ2Sf0om8jtYvRcSAjsOrv8mU6Q==
Date: Wed, 28 Sep 2022 14:10:52 +0000
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Hello:
In gro_tcp4_reassemble function, tcp data len is calculated:
tcp_dl = pkt->pkt_len - hdr_len;
https://github.com/DPDK/dpdk/blob/v22.07/lib/gro/gro_tcp4.c#L232

if packets < 60 bytes, pkt_len will contain padding bytes, tcp_dl is incorrectly calculated. this will result the wrong data length after gro.

diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c
index 7498c66141..cbba9fed5e 100644
--- a/lib/gro/gro_tcp4.c
+++ b/lib/gro/gro_tcp4.c
@@ -229,7 +229,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
         * Don't process the packet whose payload length is less than or
         * equal to 0.
         */
-       tcp_dl = pkt->pkt_len - hdr_len;
+       tcp_dl = rte_be_to_cpu_16(ipv4_hdr->total_length) - hdr_len;
        if (tcp_dl <= 0)
                return -1;