tty/vt: prevent registration of console with invalid number

If a user specifies an invalid console like 'console=tty3000',
the vt driver should prevent setting up a vt entry for that.
Suggested-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Link: https://lore.kernel.org/r/20221209112737.3222509-3-svens@linux.ibm.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/vt.c

@@ -3156,8 +3156,14 @@ static struct tty_driver *vt_console_device(struct console *c, int *index)
 	return console_driver;
 }
 
+static int vt_console_setup(struct console *co, char *options)
+{
+	return co->index >= MAX_NR_CONSOLES ? -EINVAL : 0;
+}
+
 static struct console vt_console_driver = {
 	.name		= "tty",
+	.setup		= vt_console_setup,
 	.write		= vt_console_print,
 	.device		= vt_console_device,
 	.unblank	= unblank_screen,