net: ena: fix NULL dereference due to untimely napi initialization

[ Upstream commit 78a55d05 ]

napi poll functions should be initialized before running request_irq(),
to handle a rare condition where there is a pending interrupt, causing
the ISR to fire immediately while the poll function wasn't set yet,
causing a NULL dereference.

Fixes: 1738cd3e ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -1482,8 +1482,6 @@ static int ena_up_complete(struct ena_adapter *adapter)
 	if (rc)
 		return rc;
 
-	ena_init_napi(adapter);
-
 	ena_change_mtu(adapter->netdev, adapter->netdev->mtu);
 
 	ena_refill_all_rx_bufs(adapter);
@@ -1643,6 +1641,13 @@ static int ena_up(struct ena_adapter *adapter)
 
 	ena_setup_io_intr(adapter);
 
+	/* napi poll functions should be initialized before running
+	 * request_irq(), to handle a rare condition where there is a pending
+	 * interrupt, causing the ISR to fire immediately while the poll
+	 * function wasn't set yet, causing a null dereference
+	 */
+	ena_init_napi(adapter);
+
 	rc = ena_request_io_irq(adapter);
 	if (rc)
 		goto err_req_irq;