imx: Check for NULL pointer deref before calling tty_encode_baud_rate

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/serial/imx.c

@@ -924,11 +924,13 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
 	rational_best_approximation(16 * div * baud, sport->port.uartclk,
 		1 << 16, 1 << 16, &num, &denom);
 
-	tdiv64 = sport->port.uartclk;
-	tdiv64 *= num;
-	do_div(tdiv64, denom * 16 * div);
-	tty_encode_baud_rate(sport->port.info->port.tty,
-		(speed_t)tdiv64, (speed_t)tdiv64);
+	if (port->info && port->info->port.tty) {
+		tdiv64 = sport->port.uartclk;
+		tdiv64 *= num;
+		do_div(tdiv64, denom * 16 * div);
+		tty_encode_baud_rate(sport->port.info->port.tty,
+				(speed_t)tdiv64, (speed_t)tdiv64);
+	}
 
 	num -= 1;
 	denom -= 1;