linux-kernel - [PATCH 4.19 17/48] leds: lm3533: fix use-after-free on unbind

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Date:   Mon, 10 Aug 2020 17:21:39 +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 4.19 17/48] leds: lm3533: fix use-after-free on unbind

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

commit d584221e683bbd173738603b83a315f27d27d043 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: 50154e29e5cc ("leds: lm3533: 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-lm3533.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/leds/leds-lm3533.c
+++ b/drivers/leds/leds-lm3533.c
@@ -698,7 +698,7 @@ static int lm3533_led_probe(struct platf
 
 	platform_set_drvdata(pdev, led);
 
-	ret = devm_led_classdev_register(pdev->dev.parent, &led->cdev);
+	ret = led_classdev_register(pdev->dev.parent, &led->cdev);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to register LED %d\n", pdev->id);
 		return ret;
@@ -708,13 +708,18 @@ static int lm3533_led_probe(struct platf
 
 	ret = lm3533_led_setup(led, pdata);
 	if (ret)
-		return ret;
+		goto err_deregister;
 
 	ret = lm3533_ctrlbank_enable(&led->cb);
 	if (ret)
-		return ret;
+		goto err_deregister;
 
 	return 0;
+
+err_deregister:
+	led_classdev_unregister(&led->cdev);
+
+	return ret;
 }
 
 static int lm3533_led_remove(struct platform_device *pdev)
@@ -724,6 +729,7 @@ static int lm3533_led_remove(struct plat
 	dev_dbg(&pdev->dev, "%s\n", __func__);
 
 	lm3533_ctrlbank_disable(&led->cb);
+	led_classdev_unregister(&led->cdev);
 
 	return 0;
 }