netdev - [PATCH V2 net 3/4] net: ena: fix NULL dereference due to untimely napi initialization

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Message-ID: <1539073290-30270-4-git-send-email-akiyano@amazon.com>
Date:   Tue, 9 Oct 2018 11:21:29 +0300
From:   <akiyano@...zon.com>
To:     <davem@...emloft.net>, <netdev@...r.kernel.org>
CC:     Arthur Kiyanovski <akiyano@...zon.com>, <dwmw@...zon.com>,
        <zorik@...zon.com>, <matua@...zon.com>, <saeedb@...zon.com>,
        <msw@...zon.com>, <aliguori@...zon.com>, <nafea@...zon.com>,
        <gtzalik@...zon.com>, <netanel@...zon.com>, <alisaidi@...zon.com>
Subject: [PATCH V2 net 3/4] net: ena: fix NULL dereference due to untimely napi initialization

From: Arthur Kiyanovski <akiyano@...zon.com>

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: 1738cd3ed342 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Arthur Kiyanovski <akiyano@...zon.com>
---
 drivers/net/ethernet/amazon/ena/ena_netdev.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index ce18e07..d906293 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -1575,8 +1575,6 @@ 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);
@@ -1730,6 +1728,13 @@ 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;
-- 
2.7.4