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staging: greybus: uart: fix tty use after free

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commit 92dc0b1f46 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: a18e151757 ("greybus: more uart work")
Cc: stable@vger.kernel.org      # 4.9
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210906124538.22358-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2021-09-06 14:45:38 +02:00 committed by Greg Kroah-Hartman
parent 70981eab3d
commit 64062fcaca
1 changed files with 32 additions and 30 deletions
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62
drivers/staging/greybus/uart.c
View file

@ -800,6 +800,17 @@ 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,
@ -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)