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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,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 89/96] serial: mxs-auart: Fix out-of-bounds access through serial port index
Date:   Thu, 24 May 2018 11:39:12 +0200
Message-Id: <20180524093610.701261507@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Geert Uytterhoeven <geert+renesas@glider.be>

[ Upstream commit dd345a31bfdec350d2593e6de5964e55c7f19c76 ]

The auart_port[] array is indexed using a value derived from the
"serialN" alias in DT, or from platform data, which may lead to an
out-of-bounds access.

Fix this by adding a range check.

Fixes: 1ea6607d4cdc9179 ("serial: mxs-auart: Allow device tree probing")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/mxs-auart.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1664,6 +1664,10 @@ static int mxs_auart_probe(struct platfo
 		s->port.line = pdev->id < 0 ? 0 : pdev->id;
 	else if (ret < 0)
 		return ret;
+	if (s->port.line >= ARRAY_SIZE(auart_port)) {
+		dev_err(&pdev->dev, "serial%d out of range\n", s->port.line);
+		return -EINVAL;
+	}
 
 	if (of_id) {
 		pdev->id_entry = of_id->data;