linux-kernel - [PATCH] gpio: mockup: fix NULL pointer dereference when removing debugfs

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Date:   Tue, 20 Sep 2022 09:18:41 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Wei Yongjun <weiyongjun1@...wei.com>, stable@...r.kernel.org
Subject: [PATCH] gpio: mockup: fix NULL pointer dereference when removing debugfs

We now remove the device's debugfs entries when unbinding the driver.
This now causes a NULL-pointer dereference on module exit because the
platform devices are unregistered *after* the global debugfs directory
has been recursively removed. Fix it by unregistering the devices first.

Fixes: 303e6da99429 ("gpio: mockup: remove gpio debugfs when remove device")
Cc: Wei Yongjun <weiyongjun1@...wei.com>
Cc: stable@...r.kernel.org
Signed-off-by: Bartosz Golaszewski <brgl@...ev.pl>
---
 drivers/gpio/gpio-mockup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index a2e505a7545c..ab89cd8ddbd8 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -597,9 +597,9 @@ static int __init gpio_mockup_init(void)
 
 static void __exit gpio_mockup_exit(void)
 {
+	gpio_mockup_unregister_pdevs();
 	debugfs_remove_recursive(gpio_mockup_dbg_dir);
 	platform_driver_unregister(&gpio_mockup_driver);
-	gpio_mockup_unregister_pdevs();
 }
 
 module_init(gpio_mockup_init);
-- 
2.34.1