linux-kernel - [PATCH 7/9] serial: sh-sci: Fix out-of-bounds access through DT alias

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Message-Id: <1519119624-1268-8-git-send-email-geert+renesas@glider.be>
Date:   Tue, 20 Feb 2018 10:40:22 +0100
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Barry Song <baohua@...nel.org>, Vineet Gupta <vgupta@...opsys.com>,
        Jiri Slaby <jslaby@...e.com>,
        Michal Simek <michal.simek@...inx.com>,
        linux-serial@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        linux-renesas-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH 7/9] serial: sh-sci: Fix out-of-bounds access through DT alias

The sci_ports[] array is indexed using a value derived from the
"serialN" alias in DT, 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_SH_SCI_NR_UARTS), so this can even be triggered using a
legitimate DTB.

Fixes: f650cdf1c115498e ("serial: sh-sci: Fix out-of-bounds access through DT alias")
Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
 drivers/tty/serial/sh-sci.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 4d14f321cbec95e0..0fb4784860da6188 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -3620,6 +3620,10 @@ static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
 		dev_err(&pdev->dev, "failed to get alias id (%d)\n", id);
 		return NULL;
 	}
+	if (id >= SCI_NPORTS) {
+		dev_err(&pdev->dev, "serial%d out of range\n", id);
+		return NULL;
+	}
 
 	sp = &sci_ports[id];
 	*dev_id = id;
-- 
2.7.4