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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>,
        Michal Simek <michal.simek@xilinx.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 87/96] serial: xuartps: Fix out-of-bounds access through DT alias
Date:   Thu, 24 May 2018 11:39:10 +0200
Message-Id: <20180524093610.542857764@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 e7d75e18d0fc3f7193b65282b651f980c778d935 ]

The cdns_uart_port[] 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.

Fixes: 928e9263492069ee ("tty: xuartps: Initialize ports according to aliases")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/xilinx_uartps.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1106,7 +1106,7 @@ static struct uart_port *cdns_uart_get_p
 	struct uart_port *port;
 
 	/* Try the given port id if failed use default method */
-	if (cdns_uart_port[id].mapbase != 0) {
+	if (id < CDNS_UART_NR_PORTS && cdns_uart_port[id].mapbase != 0) {
 		/* Find the next unused port */
 		for (id = 0; id < CDNS_UART_NR_PORTS; id++)
 			if (cdns_uart_port[id].mapbase == 0)