On Wed, Jul 25, 2018 at 12:22:16AM +0900, Tetsuo Handa wrote: > >From 118c64e86641a97d44dec39e313a95b12d9bc3b2 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Date: Wed, 25 Jul 2018 00:15:18 +0900 > Subject: [PATCH v2] n_tty: Protect tty->disc_data using refcount. > > syzbot is reporting NULL pointer dereference at n_tty_set_termios() [1]. > This is because ioctl(TIOCVHANGUP) versus ioctl(TCSETS) can race. > > Since we don't want to introduce new locking dependency, this patch > converts "struct n_tty_data *ldata = tty->disc_data;" in individual > function into a function argument which follows "struct tty *", and > holds tty->disc_data at each "struct tty_ldisc_ops" hook using refcount > in order to ensure that memory which contains "struct n_tty_data" will > not be released while processing individual function. > > [1] https://syzkaller.appspot.com/bug?id=1e850009fca0b64ce49dc16499bda4f7de0ab1a5 > > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > --- > drivers/tty/n_tty.c | 511 ++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 314 insertions(+), 197 deletions(-) What changed from v1? I haven't had the chance to review your first patch, sorry, it's still in my queue. I was hoping that someone else would help out with that as well :) thanks, greg k-h
