[PATCH 1/2] serial: ma35d1: Validate console index before assignment

[Andi Shyti <andi.shyti@kernel.org>]

The console is immediately assigned to the ma35d1 port without
checking its index. This oversight can lead to out-of-bounds
errors when the index falls outside the valid '0' to
MA35_UART_NR range. Such scenario trigges ran error like the
following:

 UBSAN: array-index-out-of-bounds in drivers/tty/serial/ma35d1_serial.c:555:51
 index -1 is out of range for type 'uart_ma35d1_port [17]

Check the index before using it and bail out with a warning.

Fixes: 930cbf92db01 ("tty: serial: Add Nuvoton ma35d1 serial driver support")
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Cc: Jacky Huang <ychuang3@nuvoton.com>
Cc: <stable@vger.kernel.org> # v6.5+
---
 drivers/tty/serial/ma35d1_serial.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/ma35d1_serial.c b/drivers/tty/serial/ma35d1_serial.c
index a6a7c405892e8..21b574f78b861 100644
--- a/drivers/tty/serial/ma35d1_serial.c
+++ b/drivers/tty/serial/ma35d1_serial.c
@@ -552,11 +552,19 @@ static void ma35d1serial_console_putchar(struct uart_port *port, unsigned char c
  */
 static void ma35d1serial_console_write(struct console *co, const char *s, u32 count)
 {
-	struct uart_ma35d1_port *up = &ma35d1serial_ports[co->index];
+	struct uart_ma35d1_port *up;
 	unsigned long flags;
 	int locked = 1;
 	u32 ier;
 
+	if ((co->index < 0) || (co->index >= MA35_UART_NR)) {
+		pr_warn("Failed to write on ononsole port %x, out of range\n",
+			co->index);
+		return;
+	}
+
+	up = &ma35d1serial_ports[co->index];
+
 	if (up->port.sysrq)
 		locked = 0;
 	else if (oops_in_progress)
-- 
2.43.0