[PATCH AUTOSEL 4.18 17/27] net: ena: fix NULL dereference due to untimely napi initialization

From: Sasha Levin
Date: Mon Oct 22 2018 - 06:20:04 EST


From: Arthur Kiyanovski <akiyano@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 72dbdebf4b5d..000f0d42a710 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -1580,8 +1580,6 @@ 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);
@@ -1735,6 +1733,13 @@ 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