[PATCH 04/13] net/bnxt: add check for number of segs

[Ajit Khaparde]

From: Somnath Kotur <somnath.kotur at broadcom.com>

If the application passes incorrect number of segs for a Tx pkt i.e.
sets it to 5 while actually sending down only a single mbuf, this could
escape all the existing driver checks and driver could end up sending
down garbage TX BDs to the HW. This in turn could lead to a Tx pipeline
stall.
Fix it by validating the number of segs passed for the Tx pkt against
what is actually set by the application to prevent this.

Signed-off-by: Somnath Kotur <somnath.kotur at broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde at broadcom.com>
---
 drivers/net/bnxt/bnxt_txr.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/net/bnxt/bnxt_txr.c b/drivers/net/bnxt/bnxt_txr.c
index 6d7e9962ce..51d3689e9c 100644
--- a/drivers/net/bnxt/bnxt_txr.c
+++ b/drivers/net/bnxt/bnxt_txr.c
@@ -194,6 +194,21 @@ bnxt_check_pkt_needs_ts(struct rte_mbuf *m)
 	return false;
 }
 
+static bool
+bnxt_invalid_nb_segs(struct rte_mbuf *tx_pkt)
+{
+	uint16_t nb_segs = 1;
+	struct rte_mbuf *m_seg;
+
+	m_seg = tx_pkt->next;
+	while (m_seg) {
+		nb_segs++;
+		m_seg = m_seg->next;
+	}
+
+	return (nb_segs != tx_pkt->nb_segs);
+}
+
 static uint16_t bnxt_start_xmit(struct rte_mbuf *tx_pkt,
 				struct bnxt_tx_queue *txq,
 				uint16_t *coal_pkts,
@@ -221,6 +236,9 @@ static uint16_t bnxt_start_xmit(struct rte_mbuf *tx_pkt,
 	if (unlikely(is_bnxt_in_error(txq->bp)))
 		return -EIO;
 
+	if (unlikely(bnxt_invalid_nb_segs(tx_pkt)))
+		return -EINVAL;
+
 	long_bd = bnxt_xmit_need_long_bd(tx_pkt, txq);
 	nr_bds = long_bd + tx_pkt->nb_segs;
 
-- 
2.39.5 (Apple Git-154)