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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 3.18 168/185] serial: samsung: Fix out-of-bounds access through serial port index
Date:   Mon, 28 May 2018 12:03:29 +0200
Message-Id: <20180528100113.127942563@linuxfoundation.org>
In-Reply-To: <20180528100050.700971285@linuxfoundation.org>
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3.18-stable review patch.  If anyone has any objections, please let me know.

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

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

[ Upstream commit 49ee23b71877831ac087d6083f6f397dc19c9664 ]

The s3c24xx_serial_ports[] array is indexed using a value derived from
the "serialN" alias in DT, or from an incrementing probe index, which
may lead to an out-of-bounds access.

Fix this by adding a range check.

Note that the array size is defined by a Kconfig symbol
(CONFIG_SERIAL_SAMSUNG_UARTS), so this can even be triggered using
a legitimate DTB or legitimate board code.

Fixes: 13a9f6c64fdc55eb ("serial: samsung: Consider DT alias when probing ports")
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/samsung.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1288,6 +1288,10 @@ static int s3c24xx_serial_probe(struct p
 
 	dbg("s3c24xx_serial_probe(%p) %d\n", pdev, index);
 
+	if (index >= ARRAY_SIZE(s3c24xx_serial_ports)) {
+		dev_err(&pdev->dev, "serial%d out of range\n", index);
+		return -EINVAL;
+	}
 	ourport = &s3c24xx_serial_ports[index];
 
 	ourport->drv_data = s3c24xx_get_driver_data(pdev);