[PATCH net-next] net/ionic: avoid OOB TX partner lookup for hwstamp RXQ

[Anand Khoje]

The dedicated hardware timestamp RX queue is allocated with q->index
equal to lif->ionic->nrxqs_per_lif. The normal txqcqs array only
contains the regular queue pairs, so using that index to set rxq->partner
can read one entry past txqcqs[] and then write through the derived
pointer.
Only link RX/TX partners for normal queue-pair indexes. Leave the hwstamp
RX queue unpaired, and make the XDP_TX path abort cleanly if an RX queue
has no TX partner.

Fixes: e1615dda41144 ("net/ethernet/pensando: Add out-of-tree network drivers")
Signed-off-by: Anand Khoje <anand.a.khoje@xxxxxxxxxx>
Reviewed-by: Si-Wei Liu <si-wei.liu@xxxxxxxxxx>
---
 drivers/net/ethernet/pensando/ionic/ionic_lif.c  | 14 ++++++++++++++
 drivers/net/ethernet/pensando/ionic/ionic_txrx.c |  7 ++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.c b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
index fd3ee9820531..1822361e1070 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
@@ -920,9 +920,23 @@ static int ionic_lif_rxq_init(struct ionic_lif *lif, struct ionic_qcq *qcq)
 	};
 	int err;
 
+	q->partner = NULL;
+
+	/* Only normal RX queues have matching TX queue partners,
+	 * skip partner pairing for hwstamp RX queue.
+	 */
+	if (q->index >= lif->nxqs)
+		goto skip_partner;
+
+	if (WARN_ON_ONCE(!lif->txqcqs ||
+	    q->index >= lif->ionic->ntxqs_per_lif ||
+	    !lif->txqcqs[q->index]))
+		return -EINVAL;
+
 	q->partner = &lif->txqcqs[q->index]->q;
 	q->partner->partner = q;
 
+skip_partner:
 	if (!lif->xdp_prog ||
 	    (lif->xdp_prog->aux && lif->xdp_prog->aux->xdp_has_frags))
 		ctx.cmd.q_init.flags |= cpu_to_le16(IONIC_QINIT_F_SG);
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
index 301ebee2fdc5..73998d61593a 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
@@ -545,13 +545,18 @@ static bool ionic_run_xdp(struct ionic_rx_stats *stats,
 		break;
 
 	case XDP_TX:
+		txq = rxq->partner;
+		if (unlikely(!txq)) {
+			err = -EIO;
+			break;
+		}
+
 		xdpf = xdp_convert_buff_to_frame(&xdp_buf);
 		if (!xdpf) {
 			err = -ENOSPC;
 			break;
 		}
 
-		txq = rxq->partner;
 		nq = netdev_get_tx_queue(netdev, txq->index);
 		__netif_tx_lock(nq, smp_processor_id());
 		txq_trans_cond_update(nq);
-- 
2.52.0