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+rene...@glider.be>
---
v2:
  - Fix Fixes reference.
---
 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 b9b2bc76bcac606c..abcb4d09a2d866d0 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)
-- 
2.7.4

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