linux-kernel - [PATCH] rtc: fix RTC removal

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Message-Id: <20201205231449.610980-1-alexandre.belloni@bootlin.com>
Date:   Sun,  6 Dec 2020 00:14:48 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] rtc: fix RTC removal

Since the rtc_register_device, removing an RTC device will end with a
refcount_t: underflow; use-after-free warning since put_device is called
twice in the device tear down path.

Fixes: fdcfd854333b ("rtc: rework rtc_register_device() resource management")
Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
---
 drivers/rtc/class.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index e6b44b7c4ad3..5c6748dfa55d 100644
--- a/drivers/rtc/class.c
+++ b/drivers/rtc/class.c
@@ -335,7 +335,6 @@ static void devm_rtc_unregister_device(void *data)
 	cdev_device_del(&rtc->char_dev, &rtc->dev);
 	rtc->ops = NULL;
 	mutex_unlock(&rtc->ops_lock);
-	put_device(&rtc->dev);
 }
 
 static void devm_rtc_release_device(void *res)
-- 
2.28.0