| From 27cfb3a53be46a54ec5e0bd04e51995b74c90343 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Date: Sun, 20 Jan 2019 10:46:58 +0100 |
| Subject: tty: Handle problem if line discipline does not have receive_buf |
| |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| commit 27cfb3a53be46a54ec5e0bd04e51995b74c90343 upstream. |
| |
| Some tty line disciplines do not have a receive buf callback, so |
| properly check for that before calling it. If they do not have this |
| callback, just eat the character quietly, as we can't fail this call. |
| |
| Reported-by: Jann Horn <jannh@google.com> |
| Cc: stable <stable@vger.kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/tty/tty_io.c | 3 ++- |
| 1 file changed, 2 insertions(+), 1 deletion(-) |
| |
| --- a/drivers/tty/tty_io.c |
| +++ b/drivers/tty/tty_io.c |
| @@ -2297,7 +2297,8 @@ static int tiocsti(struct tty_struct *tt |
| return -EFAULT; |
| tty_audit_tiocsti(tty, ch); |
| ld = tty_ldisc_ref_wait(tty); |
| - ld->ops->receive_buf(tty, &ch, &mbz, 1); |
| + if (ld->ops->receive_buf) |
| + ld->ops->receive_buf(tty, &ch, &mbz, 1); |
| tty_ldisc_deref(ld); |
| return 0; |
| } |
