net/octeontx2: fix corruption in segments list

On Tx, lastseg->next is not being reset to null for multi segmented
packet and same mbuf can be used on Rx which has a stale mbuf entry into
mbuf->next.

On Rx, application receives mbuf with mbuf->next uninitialized though
mbuf->nb_segs is correct. Application iterates over all segments using
mbuf->next ignoring mbuf->nb_segs which leads to undefined behavior.

So earlier assumption of just having right value in mbuf->nb_segs is
enough, is incorrect. Mbuf must contain valid and synced value in
nb_segs and next pointer.

Fixes: 364eb0e46683 ("net/octeontx2: avoid per packet barrier with multi segment")
Cc: stable@dpdk.org
Signed-off-by: Sunil Kumar Kori <skori@marvell.com>
Acked-by: Nithin Dabilpuram <ndabilpuram@marvell.com>

diff --git a/drivers/net/octeontx2/otx2_rx.c b/drivers/net/octeontx2/otx2_rx.c
index 2da8efe..ffeade5 100644 (file)
--- a/drivers/net/octeontx2/otx2_rx.c
+++ b/drivers/net/octeontx2/otx2_rx.c
@@ -279,6 +279,12 @@ nix_recv_pkts_vector(void *rx_queue, struct rte_mbuf **rx_pkts,
                vst1q_u64((uint64_t *)mbuf2->rearm_data, rearm2);
                vst1q_u64((uint64_t *)mbuf3->rearm_data, rearm3);
 
+               /* Update that no more segments */
+               mbuf0->next = NULL;
+               mbuf1->next = NULL;
+               mbuf2->next = NULL;
+               mbuf3->next = NULL;
+
                /* Store the mbufs to rx_pkts */
                vst1q_u64((uint64_t *)&rx_pkts[packets], mbuf01);
                vst1q_u64((uint64_t *)&rx_pkts[packets + 2], mbuf23);

diff --git a/drivers/net/octeontx2/otx2_rx.h b/drivers/net/octeontx2/otx2_rx.h
index 926f614..0ba3d3d 100644 (file)
--- a/drivers/net/octeontx2/otx2_rx.h
+++ b/drivers/net/octeontx2/otx2_rx.h
@@ -215,6 +215,7 @@ nix_cqe_xtract_mseg(const struct nix_rx_parse_s *rx,
                        iova_list = (const rte_iova_t *)(iova_list + 1);
                }
        }
+       mbuf->next = NULL;
 }
 
 static __rte_always_inline uint16_t
@@ -330,10 +331,12 @@ otx2_nix_cqe_to_mbuf(const struct nix_cqe_hdr_s *cq, const uint32_t tag,
        *(uint64_t *)(&mbuf->rearm_data) = val;
        mbuf->pkt_len = len;
 
-       if (flag & NIX_RX_MULTI_SEG_F)
+       if (flag & NIX_RX_MULTI_SEG_F) {
                nix_cqe_xtract_mseg(rx, mbuf, val);
-       else
+       } else {
                mbuf->data_len = len;
+               mbuf->next = NULL;
+       }
 }
 
 #define CKSUM_F NIX_RX_OFFLOAD_CHECKSUM_F