serial: ma35d1: Validate console index before assignment

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+
Link: https://lore.kernel.org/r/20231204163804.1331415-2-andi.shyti@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/ma35d1_serial.c b/drivers/tty/serial/ma35d1_serial.c
index a6a7c405892e80e07a1ab4008a3c67619f707001..21b574f78b8615bfa3fdc1cb00790b13900349f5 100644 (file)
--- 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)