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From: Curtis Klein <curtis.klein@hpe.com>
To: wim@linux-watchdog.org, linux@roeck-us.net
Cc: linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org,
	Curtis Klein <curtis.klein@hpe.com>
Subject: [PATCH] watchdog: Fix NULL pointer dereference when releasing cdev
Date: Tue, 22 Jun 2021 23:26:23 -0700	[thread overview]
Message-ID: <1624429583-5720-1-git-send-email-curtis.klein@hpe.com> (raw)

watchdog_hrtimer_pretimeout_stop needs the watchdog device to have a
valid pointer to the watchdog core data to stop the pretimeout hrtimer.
Therefore it needs to be called before the pointers are cleared in
watchdog_cdev_unregister.

Fixes: 7b7d2fdc8c3e ("watchdog: Add hrtimer-based pretimeout feature")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Curtis Klein <curtis.klein@hpe.com>
---
 drivers/watchdog/watchdog_dev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 3bab324..ffd8f1a 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -1096,6 +1096,8 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
 		watchdog_stop(wdd);
 	}
 
+	watchdog_hrtimer_pretimeout_stop(wdd);
+
 	mutex_lock(&wd_data->lock);
 	wd_data->wdd = NULL;
 	wdd->wd_data = NULL;
@@ -1103,7 +1105,6 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
 
 	hrtimer_cancel(&wd_data->timer);
 	kthread_cancel_work_sync(&wd_data->work);
-	watchdog_hrtimer_pretimeout_stop(wdd);
 
 	put_device(&wd_data->dev);
 }
-- 
2.7.4


             reply	other threads:[~2021-06-23  6:27 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-23  6:26 Curtis Klein [this message]
2021-06-23 11:31 ` [PATCH] watchdog: Fix NULL pointer dereference when releasing cdev Guenter Roeck

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