Hi Jiayu,
Can you please  suggest if the patch can be used ? When timestamps are disabled we would unnecessarily indulge pure TCP ack packets in the GRO layer. Or can we have a fix where if the TCP timestamp option is not present in the packet, do not process the packet, return immediately ?

Thanks,
Param

On Mon, Apr 25, 2022 at 11:36 PM kumaraparameshwaran rathinavel <kumaraparamesh92@gmail.com> wrote:
Hi,

I would like you to review this patch and let me know what you think of it.

Thanks,
Kumara.

---------- Forwarded message ---------
From: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
Date: Sun, Apr 3, 2022 at 5:20 PM
Subject: [PATCH v1] gro: bug fix in identifying 0 length tcp packets
To: <jiayu.hu@intel.com>
Cc: <dev@dpdk.org>, Kumara Parameshwaran <kumaraparamesh92@gmail.com>, <stable@dpdk.org>, Kumara Parameshwaran <kparameshwar@vmware.com>


As the minimum Ethernet frame size is 64 bytes, a 0 length
tcp payload without tcp options would be 54 bytes and hence
there would be padding. So it would be incorrect to use the
packet length to determine the tcp data length.

Fixes: 1e4cf4d6d4fb ("gro: cleanup")
Cc: stable@dpdk.org

Signed-off-by: Kumara Parameshwaran <kparameshwar@vmware.com>
---
v1:
        Do not use packet length to determine the tcp data length as
        the packet length could have padded bytes. This would lead
        to addition of 0 length tcp packets into the GRO layer when
        there ethernet fram is padded.
 lib/gro/gro_tcp4.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c
index 7498c66..45e3f48 100644
--- a/lib/gro/gro_tcp4.c
+++ b/lib/gro/gro_tcp4.c
@@ -198,7 +198,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
        struct rte_tcp_hdr *tcp_hdr;
        uint32_t sent_seq;
        int32_t tcp_dl;
-       uint16_t ip_id, hdr_len, frag_off;
+       uint16_t ip_id, frag_off;
        uint8_t is_atomic;

        struct tcp4_flow_key key;
@@ -217,7 +217,6 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
        eth_hdr = rte_pktmbuf_mtod(pkt, struct rte_ether_hdr *);
        ipv4_hdr = (struct rte_ipv4_hdr *)((char *)eth_hdr + pkt->l2_len);
        tcp_hdr = (struct rte_tcp_hdr *)((char *)ipv4_hdr + pkt->l3_len);
-       hdr_len = pkt->l2_len + pkt->l3_len + pkt->l4_len;

        /*
         * Don't process the packet which has FIN, SYN, RST, PSH, URG, ECE
@@ -229,7 +228,7 @@ 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) - (pkt->l3_len + pkt->l4_len);
        if (tcp_dl <= 0)
                return -1;

--
2.7.4