linux-kernel - [PATCH 5.8 29/38] leds: 88pm860x: fix use-after-free on unbind

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Message-Id: <20200810151805.342635725@linuxfoundation.org>
Date:   Mon, 10 Aug 2020 17:19:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Amitoj Kaur Chawla <amitoj1606@...il.com>,
        Johan Hovold <johan@...nel.org>, Pavel Machek <pavel@....cz>
Subject: [PATCH 5.8 29/38] leds: 88pm860x: fix use-after-free on unbind

From: Johan Hovold <johan@...nel.org>

commit eca21c2d8655387823d695b26e6fe78cf3975c05 upstream.

Several MFD child drivers register their class devices directly under
the parent device. This means you cannot blindly do devres conversions
so that deregistration ends up being tied to the parent device,
something which leads to use-after-free on driver unbind when the class
device is released while still being registered.

Fixes: 375446df95ee ("leds: 88pm860x: Use devm_led_classdev_register")
Cc: stable <stable@...r.kernel.org>     # 4.6
Cc: Amitoj Kaur Chawla <amitoj1606@...il.com>
Signed-off-by: Johan Hovold <johan@...nel.org>
Signed-off-by: Pavel Machek <pavel@....cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/leds/leds-88pm860x.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/drivers/leds/leds-88pm860x.c
+++ b/drivers/leds/leds-88pm860x.c
@@ -203,21 +203,33 @@ static int pm860x_led_probe(struct platf
 	data->cdev.brightness_set_blocking = pm860x_led_set;
 	mutex_init(&data->lock);
 
-	ret = devm_led_classdev_register(chip->dev, &data->cdev);
+	ret = led_classdev_register(chip->dev, &data->cdev);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Failed to register LED: %d\n", ret);
 		return ret;
 	}
 	pm860x_led_set(&data->cdev, 0);
+
+	platform_set_drvdata(pdev, data);
+
 	return 0;
 }
 
+static int pm860x_led_remove(struct platform_device *pdev)
+{
+	struct pm860x_led *data = platform_get_drvdata(pdev);
+
+	led_classdev_unregister(&data->cdev);
+
+	return 0;
+}
 
 static struct platform_driver pm860x_led_driver = {
 	.driver	= {
 		.name	= "88pm860x-led",
 	},
 	.probe	= pm860x_led_probe,
+	.remove	= pm860x_led_remove,
 };
 
 module_platform_driver(pm860x_led_driver);