This is a note to let you know that I've just added the patch titled

tty: Handle problem if line discipline does not have receive_buf

to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

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

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(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 23c6fd238422..21ffcce16927 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -2189,7 +2189,8 @@ static int tiocsti(struct tty_struct *tty, char __user *p) ld = tty_ldisc_ref_wait(tty); if (!ld) return -EIO; - 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; }