linux-kernel - [PATCH 4.19 08/32] s390/ctcm: fix variable dereferenced before check

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Message-Id: <20220516193615.024944143@linuxfoundation.org>
Date:   Mon, 16 May 2022 21:36:22 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Colin Ian King <colin.i.king@...il.com>,
        Alexandra Winter <wintera@...ux.ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 08/32] s390/ctcm: fix variable dereferenced before check

From: Alexandra Winter <wintera@...ux.ibm.com>

[ Upstream commit 2c50c6867c85afee6f2b3bcbc50fc9d0083d1343 ]

Found by cppcheck and smatch.
smatch complains about
drivers/s390/net/ctcm_sysfs.c:43 ctcm_buffer_write() warn: variable dereferenced before check 'priv' (see line 42)

Fixes: 3c09e2647b5e ("ctcm: rename READ/WRITE defines to avoid redefinitions")
Reported-by: Colin Ian King <colin.i.king@...il.com>
Signed-off-by: Alexandra Winter <wintera@...ux.ibm.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/s390/net/ctcm_sysfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/net/ctcm_sysfs.c b/drivers/s390/net/ctcm_sysfs.c
index ded1930a00b2..e3813a7aa5e6 100644
--- a/drivers/s390/net/ctcm_sysfs.c
+++ b/drivers/s390/net/ctcm_sysfs.c
@@ -39,11 +39,12 @@ static ssize_t ctcm_buffer_write(struct device *dev,
 	struct ctcm_priv *priv = dev_get_drvdata(dev);
 	int rc;
 
-	ndev = priv->channel[CTCM_READ]->netdev;
-	if (!(priv && priv->channel[CTCM_READ] && ndev)) {
+	if (!(priv && priv->channel[CTCM_READ] &&
+	      priv->channel[CTCM_READ]->netdev)) {
 		CTCM_DBF_TEXT(SETUP, CTC_DBF_ERROR, "bfnondev");
 		return -ENODEV;
 	}
+	ndev = priv->channel[CTCM_READ]->netdev;
 
 	rc = kstrtouint(buf, 0, &bs1);
 	if (rc)
-- 
2.35.1