1 files changed, 61 insertions, 4 deletions

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index de06c3c2ff70..3149114bf130 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2255,6 +2255,7 @@ static int tty_fasync(int fd, struct file *filp, int on)
 	return retval;
 }
 
+static bool tty_legacy_tiocsti __read_mostly = IS_ENABLED(CONFIG_LEGACY_TIOCSTI);
 /**
  * tiocsti		-	fake input character
  * @tty: tty to fake input into
@@ -2273,6 +2274,9 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
 	char ch, mbz = 0;
 	struct tty_ldisc *ld;
 
+	if (!tty_legacy_tiocsti)
+		return -EIO;
+
 	if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (get_user(ch, p))
@@ -3494,7 +3498,7 @@ void tty_default_fops(struct file_operations *fops)
 	*fops = tty_fops;
 }
 
-static char *tty_devnode(struct device *dev, umode_t *mode)
+static char *tty_devnode(const struct device *dev, umode_t *mode)
 {
 	if (!mode)
 		return NULL;
@@ -3526,7 +3530,14 @@ static ssize_t show_cons_active(struct device *dev,
 	struct console *c;
 	ssize_t count = 0;
 
-	console_lock();
+	/*
+	 * Hold the console_list_lock to guarantee that no consoles are
+	 * unregistered until all console processing is complete.
+	 * This also allows safe traversal of the console list and
+	 * race-free reading of @flags.
+	 */
+	console_list_lock();
+
 	for_each_console(c) {
 		if (!c->device)
 			continue;
@@ -3538,6 +3549,13 @@ static ssize_t show_cons_active(struct device *dev,
 		if (i >= ARRAY_SIZE(cs))
 			break;
 	}
+
+	/*
+	 * Take console_lock to serialize device() callback with
+	 * other console operations. For example, fg_console is
+	 * modified under console_lock when switching vt.
+	 */
+	console_lock();
 	while (i--) {
 		int index = cs[i]->index;
 		struct tty_driver *drv = cs[i]->device(cs[i], &index);
@@ -3553,6 +3571,8 @@ static ssize_t show_cons_active(struct device *dev,
 	}
 	console_unlock();
 
+	console_list_unlock();
+
 	return count;
 }
 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
@@ -3572,13 +3592,51 @@ void console_sysfs_notify(void)
 		sysfs_notify(&consdev->kobj, NULL, "active");
 }
 
+static struct ctl_table tty_table[] = {
+	{
+		.procname	= "legacy_tiocsti",
+		.data		= &tty_legacy_tiocsti,
+		.maxlen		= sizeof(tty_legacy_tiocsti),
+		.mode		= 0644,
+		.proc_handler	= proc_dobool,
+	},
+	{
+		.procname	= "ldisc_autoload",
+		.data		= &tty_ldisc_autoload,
+		.maxlen		= sizeof(tty_ldisc_autoload),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+	{ }
+};
+
+static struct ctl_table tty_dir_table[] = {
+	{
+		.procname	= "tty",
+		.mode		= 0555,
+		.child		= tty_table,
+	},
+	{ }
+};
+
+static struct ctl_table tty_root_table[] = {
+	{
+		.procname	= "dev",
+		.mode		= 0555,
+		.child		= tty_dir_table,
+	},
+	{ }
+};
+
 /*
  * Ok, now we can initialize the rest of the tty devices and can count
  * on memory allocations, interrupts etc..
  */
 int __init tty_init(void)
 {
-	tty_sysctl_init();
+	register_sysctl_table(tty_root_table);
 	cdev_init(&tty_cdev, &tty_fops);
 	if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
 	    register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
@@ -3600,4 +3658,3 @@ int __init tty_init(void)
 #endif
 	return 0;
 }
-