From bc6605892b9683a0d3b12e3527bf25efb21ba801 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Fri, 17 Apr 2020 11:27:37 +0800 Subject: [PATCH] serdev: ttyport: restore client ops on deregistration commit 0c5aae59270fb1f827acce182786094c9ccf598e upstream. The serdev tty-port controller driver should reset the tty-port client operations also on deregistration to avoid a NULL-pointer dereference in case the port is later re-registered as a normal tty device. Note that this can only happen with tty drivers such as 8250 which have statically allocated port structures that can end up being reused and where a later registration would not register a serdev controller (e.g. due to registration errors or if the devicetree has been changed in between). Specifically, this can be an issue for any statically defined ports that would be registered by 8250 core when an 8250 driver is being unbound. Fixes: bed35c6dfa6a ("serdev: add a tty port controller driver") Cc: stable # 4.11 Reported-by: Loic Poulain Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20200210145730.22762-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yang Yingliang --- drivers/tty/serdev/serdev-ttyport.c | 6 ++---- drivers/tty/tty_port.c | 5 +++-- include/linux/tty.h | 2 ++ 3 files changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c index fa1672993b4c..048a7bcae5f9 100644 --- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -265,7 +265,6 @@ struct device *serdev_tty_port_register(struct tty_port *port, struct device *parent, struct tty_driver *drv, int idx) { - const struct tty_port_client_operations *old_ops; struct serdev_controller *ctrl; struct serport *serport; int ret; @@ -284,7 +283,6 @@ struct device *serdev_tty_port_register(struct tty_port *port, ctrl->ops = &ctrl_ops; - old_ops = port->client_ops; port->client_ops = &client_ops; port->client_data = ctrl; @@ -297,7 +295,7 @@ struct device *serdev_tty_port_register(struct tty_port *port, err_reset_data: port->client_data = NULL; - port->client_ops = old_ops; + port->client_ops = &tty_port_default_client_ops; serdev_controller_put(ctrl); return ERR_PTR(ret); @@ -312,8 +310,8 @@ int serdev_tty_port_unregister(struct tty_port *port) return -ENODEV; serdev_controller_remove(ctrl); - port->client_ops = NULL; port->client_data = NULL; + port->client_ops = &tty_port_default_client_ops; serdev_controller_put(ctrl); return 0; diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c index c699d41a2a48..fbacb00c2601 100644 --- a/drivers/tty/tty_port.c +++ b/drivers/tty/tty_port.c @@ -52,10 +52,11 @@ static void tty_port_default_wakeup(struct tty_port *port) } } -static const struct tty_port_client_operations default_client_ops = { +const struct tty_port_client_operations tty_port_default_client_ops = { .receive_buf = tty_port_default_receive_buf, .write_wakeup = tty_port_default_wakeup, }; +EXPORT_SYMBOL_GPL(tty_port_default_client_ops); void tty_port_init(struct tty_port *port) { @@ -68,7 +69,7 @@ void tty_port_init(struct tty_port *port) spin_lock_init(&port->lock); port->close_delay = (50 * HZ) / 100; port->closing_wait = (3000 * HZ) / 100; - port->client_ops = &default_client_ops; + port->client_ops = &tty_port_default_client_ops; kref_init(&port->kref); } EXPORT_SYMBOL(tty_port_init); diff --git a/include/linux/tty.h b/include/linux/tty.h index 76db046f09ab..248a137112e8 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -225,6 +225,8 @@ struct tty_port_client_operations { void (*write_wakeup)(struct tty_port *port); }; +extern const struct tty_port_client_operations tty_port_default_client_ops; + struct tty_port { struct tty_bufhead buf; /* Locked internally */ struct tty_struct *tty; /* Back pointer */ -- GitLab