netdev - [PATCH] can: flexcan: fix an use-after-free in flexcan_setup_stop

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Date:   Sat, 6 Jul 2019 11:37:20 +0800
From:   Wen Yang <wen.yang99@....com.cn>
To:     linux-kernel@...r.kernel.org
Cc:     xue.zhihong@....com.cn, wang.yi59@....com.cn,
        cheng.shengyu@....com.cn, Wen Yang <wen.yang99@....com.cn>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>, linux-can@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [PATCH] can: flexcan: fix an use-after-free in flexcan_setup_stop_mode()

The gpr_np variable is still being used in dev_dbg() after the
of_node_put() call, which may result in use-after-free.

Fixes: de3578c198c6 ("can: flexcan: add self wakeup support")
Signed-off-by: Wen Yang <wen.yang99@....com.cn>
Cc: Wolfgang Grandegger <wg@...ndegger.com>
Cc: Marc Kleine-Budde <mkl@...gutronix.de>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: linux-can@...r.kernel.org
Cc: netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
 drivers/net/can/flexcan.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index f2fe344..33ce45d 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -1437,10 +1437,10 @@ static int flexcan_setup_stop_mode(struct platform_device *pdev)
 
 	priv = netdev_priv(dev);
 	priv->stm.gpr = syscon_node_to_regmap(gpr_np);
-	of_node_put(gpr_np);
 	if (IS_ERR(priv->stm.gpr)) {
 		dev_dbg(&pdev->dev, "could not find gpr regmap\n");
-		return PTR_ERR(priv->stm.gpr);
+		ret = PTR_ERR(priv->stm.gpr);
+		goto out_put_node;
 	}
 
 	priv->stm.req_gpr = out_val[1];
@@ -1455,7 +1455,9 @@ static int flexcan_setup_stop_mode(struct platform_device *pdev)
 
 	device_set_wakeup_capable(&pdev->dev, true);
 
-	return 0;
+out_put_node:
+	of_node_put(gpr_np);
+	return ret;
 }
 
 static const struct of_device_id flexcan_of_match[] = {
-- 
2.9.5