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Message-Id: <20210906124538.22358-1-johan@kernel.org>
Date: Mon, 6 Sep 2021 14:45:38 +0200
From: Johan Hovold <johan@...nel.org>
To: David Lin <dtwlin@...il.com>, Johan Hovold <johan@...nel.org>,
Alex Elder <elder@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: greybus-dev@...ts.linaro.org, linux-staging@...ts.linux.dev,
linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH] staging: greybus: uart: fix tty use after free
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@...r.kernel.org # 4.9
Signed-off-by: Johan Hovold <johan@...nel.org>
---
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 73f01ed1e5b7..a943fce322be 100644
--- a/drivers/staging/greybus/uart.c
+++ b/drivers/staging/greybus/uart.c
@@ -761,6 +761,17 @@ 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,
@@ -786,6 +797,7 @@ 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,
@@ -798,17 +810,11 @@ 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)) {
@@ -816,13 +822,23 @@ 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);
@@ -830,7 +846,7 @@ 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);
@@ -844,7 +860,7 @@ 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;
@@ -853,9 +869,6 @@ 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);
@@ -863,7 +876,7 @@ 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);
@@ -890,16 +903,10 @@ 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;
}
@@ -930,15 +937,10 @@ 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)
--
2.32.0
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