Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4dc56951 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

staging: greybus: uart: fix tty use after free 



commit 92dc0b1f46e12cfabd28d709bb34f7a39431b44f upstream.

User space can hold a tty open indefinitely and tty drivers must not
release the underlying structures until the last user is gone.

Switch to using the tty-port reference counter to manage the life time
of the greybus tty state to avoid use after free after a disconnect.

Fixes: a18e1517 ("greybus: more uart work")
Cc: stable@vger.kernel.org      # 4.9
Reviewed-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210906124538.22358-1-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent aa2c274c

drivers/staging/greybus/uart.c

+32 −30
Original line number Diff line number Diff line
@@ -789,6 +789,17 @@ static void gb_tty_port_shutdown(struct tty_port *port) 
	gbphy_runtime_put_autosuspend(gb_tty->gbphy_dev);

}



static void gb_tty_port_destruct(struct tty_port *port)

{

	struct gb_tty *gb_tty = container_of(port, struct gb_tty, port);



	if (gb_tty->minor != GB_NUM_MINORS)

		release_minor(gb_tty);

	kfifo_free(&gb_tty->write_fifo);

	kfree(gb_tty->buffer);

	kfree(gb_tty);

}



static const struct tty_operations gb_ops = {

	.install =		gb_tty_install,

	.open =			gb_tty_open,
@@ -814,6 +825,7 @@ static const struct tty_port_operations gb_port_ops = { 
	.dtr_rts =		gb_tty_dtr_rts,

	.activate =		gb_tty_port_activate,

	.shutdown =		gb_tty_port_shutdown,

	.destruct =		gb_tty_port_destruct,

};



static int gb_uart_probe(struct gbphy_device *gbphy_dev,
@@ -826,17 +838,11 @@ static int gb_uart_probe(struct gbphy_device *gbphy_dev, 
	int retval;

	int minor;



	gb_tty = kzalloc(sizeof(*gb_tty), GFP_KERNEL);

	if (!gb_tty)

		return -ENOMEM;



	connection = gb_connection_create(gbphy_dev->bundle,

					  le16_to_cpu(gbphy_dev->cport_desc->id),

					  gb_uart_request_handler);

	if (IS_ERR(connection)) {

		retval = PTR_ERR(connection);

		goto exit_tty_free;

	}

	if (IS_ERR(connection))

		return PTR_ERR(connection);



	max_payload = gb_operation_get_payload_size_max(connection);

	if (max_payload < sizeof(struct gb_uart_send_data_request)) {
@@ -844,13 +850,23 @@ static int gb_uart_probe(struct gbphy_device *gbphy_dev, 
		goto exit_connection_destroy;

	}



	gb_tty = kzalloc(sizeof(*gb_tty), GFP_KERNEL);

	if (!gb_tty) {

		retval = -ENOMEM;

		goto exit_connection_destroy;

	}



	tty_port_init(&gb_tty->port);

	gb_tty->port.ops = &gb_port_ops;

	gb_tty->minor = GB_NUM_MINORS;



	gb_tty->buffer_payload_max = max_payload -

			sizeof(struct gb_uart_send_data_request);



	gb_tty->buffer = kzalloc(gb_tty->buffer_payload_max, GFP_KERNEL);

	if (!gb_tty->buffer) {

		retval = -ENOMEM;

		goto exit_connection_destroy;

		goto exit_put_port;

	}



	INIT_WORK(&gb_tty->tx_work, gb_uart_tx_write_work);
@@ -858,7 +874,7 @@ static int gb_uart_probe(struct gbphy_device *gbphy_dev, 
	retval = kfifo_alloc(&gb_tty->write_fifo, GB_UART_WRITE_FIFO_SIZE,

			     GFP_KERNEL);

	if (retval)

		goto exit_buf_free;

		goto exit_put_port;



	gb_tty->credits = GB_UART_FIRMWARE_CREDITS;

	init_completion(&gb_tty->credits_complete);
@@ -872,7 +888,7 @@ static int gb_uart_probe(struct gbphy_device *gbphy_dev, 
		} else {

			retval = minor;

		}

		goto exit_kfifo_free;

		goto exit_put_port;

	}



	gb_tty->minor = minor;
@@ -881,9 +897,6 @@ static int gb_uart_probe(struct gbphy_device *gbphy_dev, 
	init_waitqueue_head(&gb_tty->wioctl);

	mutex_init(&gb_tty->mutex);



	tty_port_init(&gb_tty->port);

	gb_tty->port.ops = &gb_port_ops;



	gb_tty->connection = connection;

	gb_tty->gbphy_dev = gbphy_dev;

	gb_connection_set_data(connection, gb_tty);
@@ -891,7 +904,7 @@ static int gb_uart_probe(struct gbphy_device *gbphy_dev, 


	retval = gb_connection_enable_tx(connection);

	if (retval)

		goto exit_release_minor;

		goto exit_put_port;



	send_control(gb_tty, gb_tty->ctrlout);
@@ -918,16 +931,10 @@ static int gb_uart_probe(struct gbphy_device *gbphy_dev, 


exit_connection_disable:

	gb_connection_disable(connection);

exit_release_minor:

	release_minor(gb_tty);

exit_kfifo_free:

	kfifo_free(&gb_tty->write_fifo);

exit_buf_free:

	kfree(gb_tty->buffer);

exit_put_port:

	tty_port_put(&gb_tty->port);

exit_connection_destroy:

	gb_connection_destroy(connection);

exit_tty_free:

	kfree(gb_tty);



	return retval;

}
@@ -958,15 +965,10 @@ static void gb_uart_remove(struct gbphy_device *gbphy_dev) 
	gb_connection_disable_rx(connection);

	tty_unregister_device(gb_tty_driver, gb_tty->minor);



	/* FIXME - free transmit / receive buffers */



	gb_connection_disable(connection);

	tty_port_destroy(&gb_tty->port);

	gb_connection_destroy(connection);

	release_minor(gb_tty);

	kfifo_free(&gb_tty->write_fifo);

	kfree(gb_tty->buffer);

	kfree(gb_tty);



	tty_port_put(&gb_tty->port);

}



static int gb_tty_init(void)