From: Daniel Starke daniel.starke@siemens.com
stable inclusion from stable-v5.10.137 commit 8fd063a6085abb0b4aa8682beed8158c3952d713 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I60PLB
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ 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@siemens.com Link: https://lore.kernel.org/r/20220707113223.3685-4-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Reviewed-by: Wei Li liwei391@huawei.com --- drivers/tty/n_gsm.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index a6c0a1b76ddb..cb5ed4155a8d 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -2747,12 +2747,15 @@ 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; }