linux-kernel - [PATCH] net: hns3: fix null pointer dereference before null check

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Date:   Fri, 29 Sep 2017 20:51:23 +0100
From:   Colin King <colin.king@...onical.com>
To:     Yisen Zhuang <yisen.zhuang@...wei.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] net: hns3: fix null pointer dereference before null check

From: Colin Ian King <colin.king@...onical.com>

pointer ndev is being dereferenced with the call to netif_running
before it is being null checked.  Re-order the code to only dereference
ndev after it has been null checked.

Detected by CoverityScan, CID#1457206 ("Dereference before null check")

Fixes: 9df8f79a4d29 ("net: hns3: Add DCB support when interacting with network stack")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c
index 4a0890f98b70..c31506514e5d 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hns3_enet.c
@@ -2865,7 +2865,7 @@ static int hns3_client_setup_tc(struct hnae3_handle *handle, u8 tc)
 {
 	struct hnae3_knic_private_info *kinfo = &handle->kinfo;
 	struct net_device *ndev = kinfo->netdev;
-	bool if_running = netif_running(ndev);
+	bool if_running;
 	int ret;
 	u8 i;
 
@@ -2875,6 +2875,8 @@ static int hns3_client_setup_tc(struct hnae3_handle *handle, u8 tc)
 	if (!ndev)
 		return -ENODEV;
 
+	if_running = netif_running(ndev);
+
 	ret = netdev_set_num_tc(ndev, tc);
 	if (ret)
 		return ret;
-- 
2.14.1