[PATCH 3.16 023/366] serial: xuartps: Fix out-of-bounds access through DT alias

Ben Hutchings
2018-10-14T23:29:00Z

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

commit e7d75e18d0fc3f7193b65282b651f980c778d935 upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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
@@ -1007,7 +1007,7 @@ 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)