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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Wen Yang <wen.yang99@zte.com.cn>,
        Marc Kleine-Budde <mkl@pengutronix.de>
Subject: [PATCH 5.2 047/144] can: flexcan: fix an use-after-free in flexcan_setup_stop_mode()
Date:   Wed, 14 Aug 2019 19:00:03 +0200
Message-Id: <20190814165801.795811337@linuxfoundation.org>
In-Reply-To: <20190814165759.466811854@linuxfoundation.org>
References: <20190814165759.466811854@linuxfoundation.org>
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From: Wen Yang <wen.yang99@zte.com.cn>

commit e9f2a856e102fa27715b94bcc2240f686536d29b upstream.

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@zte.com.cn>
Cc: linux-stable <stable@vger.kernel.org> # >= v5.0
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/can/flexcan.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -1455,10 +1455,10 @@ static int flexcan_setup_stop_mode(struc
 
 	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];
@@ -1473,7 +1473,9 @@ static int flexcan_setup_stop_mode(struc
 
 	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[] = {