Commit 42fcdaa9 authored by Peter Hurley's avatar Peter Hurley Committed by Sasha Levin

n_tty: Fix unsafe reference to "other" ldisc

[ Upstream commit 6d27a63c ]

Although n_tty_check_unthrottle() has a valid ldisc reference (since
the tty core gets the ldisc ref in tty_read() before calling the line
discipline read() method), it does not have a valid ldisc reference to
the "other" pty of a pty pair. Since getting an ldisc reference for
tty->link essentially open-codes tty_wakeup(), just replace with the
equivalent tty_wakeup().

Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
parent 16c10d77
......@@ -277,16 +277,13 @@ static void n_tty_check_throttle(struct tty_struct *tty)
static void n_tty_check_unthrottle(struct tty_struct *tty)
{
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
if (tty->driver->type == TTY_DRIVER_TYPE_PTY) {
if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
return;
if (!tty->count)
return;
n_tty_set_room(tty);
n_tty_write_wakeup(tty->link);
if (waitqueue_active(&tty->link->write_wait))
wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
tty_wakeup(tty->link);
return;
}
......
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