From 64062fcaca8872f063ec9da011e7bf30470be33f Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 6 Sep 2021 14:45:38 +0200 Subject: [PATCH] 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: a18e15175708 ("greybus: more uart work") Cc: stable@vger.kernel.org # 4.9 Reviewed-by: Alex Elder Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20210906124538.22358-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/staging/greybus/uart.c | 62 ++++++++++++++++++---------------- 1 file changed, 32 insertions(+), 30 deletions(-) diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c index b0b7d4a1cee4..770fc7185ed5 100644 --- a/drivers/staging/greybus/uart.c +++ b/drivers/staging/greybus/uart.c @@ -800,6 +800,17 @@ out: 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, @@ -823,6 +834,7 @@ 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, @@ -835,17 +847,11 @@ 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)) { @@ -853,13 +859,23 @@ 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); @@ -867,7 +883,7 @@ 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); @@ -881,7 +897,7 @@ 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; @@ -890,9 +906,6 @@ 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); @@ -900,7 +913,7 @@ 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); @@ -927,16 +940,10 @@ 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; } @@ -967,15 +974,10 @@ 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) -- 2.20.1