linux-kernel - [PATCH v1 1/3] serial: 8250_exar: Avoid NULL pointer dereference at ->exit()

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Message-Id: <20210608144239.12697-1-andriy.shevchenko@linux.intel.com>
Date:   Tue,  8 Jun 2021 17:42:37 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v1 1/3] serial: 8250_exar: Avoid NULL pointer dereference at ->exit()

It's possible that during ->exit() the private_data is NULL,
for instance when there was no GPIO device instantiated.
Due to this we may not dereference it. Add a respective check.

Note, for now ->exit() only makes sense when GPIO device
was instantiated, that's why we may use the check for entire
function.

Fixes: 81171e7d31a6 ("serial: 8250_exar: Constify the software nodes")
Reported-by: Maxim Levitsky <mlevitsk@...hat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/tty/serial/8250/8250_exar.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 2f49c580139b..bd4e9f6ac29c 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -553,7 +553,11 @@ static void pci_xr17v35x_exit(struct pci_dev *pcidev)
 {
 	struct exar8250 *priv = pci_get_drvdata(pcidev);
 	struct uart_8250_port *port = serial8250_get_port(priv->line[0]);
-	struct platform_device *pdev = port->port.private_data;
+	struct platform_device *pdev;
+
+	pdev = port->port.private_data;
+	if (!pdev)
+		return;
 
 	device_remove_software_node(&pdev->dev);
 	platform_device_unregister(pdev);
-- 
2.30.2