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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Amitoj Kaur Chawla <amitoj1606@gmail.com>,
        Johan Hovold <johan@kernel.org>, Pavel Machek <pavel@ucw.cz>
Subject: [PATCH 5.8 27/38] leds: da903x: fix use-after-free on unbind
Date:   Mon, 10 Aug 2020 17:19:17 +0200
Message-Id: <20200810151805.236512093@linuxfoundation.org>
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From: Johan Hovold <johan@kernel.org>

commit 6f4aa35744f69ed9b0bf5a736c9ca9b44bc1dcea 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: eed16255d66b ("leds: da903x: Use devm_led_classdev_register")
Cc: stable <stable@vger.kernel.org>     # 4.6
Cc: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/leds/leds-da903x.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/drivers/leds/leds-da903x.c
+++ b/drivers/leds/leds-da903x.c
@@ -110,12 +110,23 @@ static int da903x_led_probe(struct platf
 	led->flags = pdata->flags;
 	led->master = pdev->dev.parent;
 
-	ret = devm_led_classdev_register(led->master, &led->cdev);
+	ret = led_classdev_register(led->master, &led->cdev);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to register LED %d\n", id);
 		return ret;
 	}
 
+	platform_set_drvdata(pdev, led);
+
+	return 0;
+}
+
+static int da903x_led_remove(struct platform_device *pdev)
+{
+	struct da903x_led *led = platform_get_drvdata(pdev);
+
+	led_classdev_unregister(&led->cdev);
+
 	return 0;
 }
 
@@ -124,6 +135,7 @@ static struct platform_driver da903x_led
 		.name	= "da903x-led",
 	},
 	.probe		= da903x_led_probe,
+	.remove		= da903x_led_remove,
 };
 
 module_platform_driver(da903x_led_driver);