linux-kernel - [PATCH][next] can: etas_es58x: Fix potential null pointer dereference on pointer cf

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Message-Id: <20210415085535.1808272-1-colin.king@canonical.com>
Date:   Thu, 15 Apr 2021 09:55:35 +0100
From:   Colin King <colin.king@...onical.com>
To:     Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] can: etas_es58x: Fix potential null pointer dereference on pointer cf

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

The pointer cf is being null checked earlier in the code, however the
update of the rx_bytes statistics is dereferencing cf without null
checking cf.  Fix this by moving the statement into the following code
block that has a null cf check.

Addresses-Coverity: ("Dereference after null check")
Fixes: 8537257874e9 ("can: etas_es58x: add core support for ETAS ES58X CAN USB interfaces")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/net/can/usb/etas_es58x/es58x_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.c b/drivers/net/can/usb/etas_es58x/es58x_core.c
index 7222b3b6ca46..5198e1d6b6ad 100644
--- a/drivers/net/can/usb/etas_es58x/es58x_core.c
+++ b/drivers/net/can/usb/etas_es58x/es58x_core.c
@@ -856,9 +856,10 @@ int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error,
 	 * consistency.
 	 */
 	netdev->stats.rx_packets++;
-	netdev->stats.rx_bytes += cf->can_dlc;
 
 	if (cf) {
+		netdev->stats.rx_bytes += cf->can_dlc;
+
 		if (cf->data[1])
 			cf->can_id |= CAN_ERR_CRTL;
 		if (cf->data[2] || cf->data[3]) {
-- 
2.30.2