serial: xuartps: Fix out-of-bounds access through DT alias

[ 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>

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 009e0db..4f2f4ac 100644 (file)
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1026,7 +1026,7 @@ 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)