leds: da903x: fix use-after-free on unbind

BugLink: https://bugs.launchpad.net/bugs/1891387
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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

diff --git a/drivers/leds/leds-da903x.c b/drivers/leds/leds-da903x.c
index ed1b303f699f5a4f3242c2dd1dd05293f93b72ae..2b5fb00438a2d3e043ef26a13da3605eabe153bf 100644 (file)
--- a/drivers/leds/leds-da903x.c
+++ b/drivers/leds/leds-da903x.c
@@ -110,12 +110,23 @@ static int da903x_led_probe(struct platform_device *pdev)
        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_driver = {
                .name   = "da903x-led",
        },
        .probe          = da903x_led_probe,
+       .remove         = da903x_led_remove,
 };
 
 module_platform_driver(da903x_led_driver);