linux-kernel - [PATCH AUTOSEL 4.9 7/9] net: ena: fix NULL dereference due to untimely napi initialization

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Message-Id: <20181022102133.41222-7-sashal@kernel.org>
Date:   Mon, 22 Oct 2018 06:21:31 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Arthur Kiyanovski <akiyano@...zon.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.9 7/9] net: ena: fix NULL dereference due to untimely napi initialization

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

[ Upstream commit 78a55d05def95144ca5fa9a64c49b2a0636a9866 ]

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>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 1d92e034febc..0c298878bf46 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/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;
-- 
2.17.1