This is a note to let you know that I've just added the patch titled tty: n_gsm: fix missing corner cases in gsmld_poll() to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tty-n_gsm-fix-missing-corner-cases-in-gsmld_poll.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit d66b4c53c229e6df90d9333fdb22c1c19f4eb067 Author: Daniel Starke <daniel.starke@xxxxxxxxxxx> Date: Thu Jul 7 13:32:23 2022 +0200 tty: n_gsm: fix missing corner cases in gsmld_poll() [ Upstream commit 7e5b4322cde067e1d0f1bf8f490e93f664a7c843 ] gsmld_poll() currently fails to handle the following corner cases correctly: - remote party closed the associated tty Add the missing checks and map those to EPOLLHUP. Reorder the checks to group them by their reaction. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Signed-off-by: Daniel Starke <daniel.starke@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20220707113223.3685-4-daniel.starke@xxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 39b6bcdc2c55..22da64453054 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -2693,12 +2693,15 @@ static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file, poll_wait(file, &tty->read_wait, wait); poll_wait(file, &tty->write_wait, wait); + + if (gsm->dead) + mask |= EPOLLHUP; if (tty_hung_up_p(file)) mask |= EPOLLHUP; + if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) + mask |= EPOLLHUP; if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0) mask |= EPOLLOUT | EPOLLWRNORM; - if (gsm->dead) - mask |= EPOLLHUP; return mask; }