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From e7d75e18d0fc3f7193b65282b651f980c778d935 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Fri, 23 Feb 2018 14:38:37 +0100
Subject: [PATCH] serial: xuartps: Fix out-of-bounds access through DT alias
Git-commit: e7d75e18d0fc3f7193b65282b651f980c778d935
Patch-mainline: v4.17-rc1
References: bsc#1051510

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/tty/serial/xilinx_uartps.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index b9b2bc76bcac..abcb4d09a2d8 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1110,7 +1110,7 @@ static struct uart_port *cdns_uart_get_port(int id)
 	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)
-- 
2.17.1