[PATCH AUTOSEL 4.14 12/15] net: ena: fix NULL dereference due to untimely napi initialization

Sasha Levin
2018-10-22T10:20:23Z

From: Arthur Kiyanovski <akiyano@amazon.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@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 | 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 08c9c99a8331..3c7813f04962 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -1571,8 +1571,6 @@ 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);
@@ -1726,6 +1724,13 @@ 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