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From: Chen-Shi-Hong <eric039eric@gmail.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org,
	Chen-Shi-Hong <eric039eric@gmail.com>
Subject: [PATCH] hwmon: (fschmd) avoid client->dev dereference in watchdog_release
Date: Sat, 23 May 2026 13:10:53 +0800	[thread overview]
Message-ID: <20260523051117.9400-1-eric039eric@gmail.com> (raw)

fschmd_remove() can detach the i2c client while the watchdog device
is still open.

If watchdog_release() later takes the unexpected-close path, it calls
watchdog_trigger() and then logs the event with dev_crit() using
data->client->dev. However, the client may already have been cleared
by the remove path.

watchdog_trigger() already checks whether data->client is still valid
and returns -ENODEV if the client is gone. Use its return value to
decide whether to emit the message, and log with watchdog_name instead
of dereferencing data->client->dev.

This avoids relying on a device pointer that may no longer be valid
during release after device removal.

Signed-off-by: Chen-Shi-Hong <eric039eric@gmail.com>
---
 drivers/hwmon/fschmd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/fschmd.c b/drivers/hwmon/fschmd.c
index 1211fa2259e5..d1e7fc72e81f 100644
--- a/drivers/hwmon/fschmd.c
+++ b/drivers/hwmon/fschmd.c
@@ -834,9 +834,9 @@ static int watchdog_release(struct inode *inode, struct file *filp)
 		watchdog_stop(data);
 		data->watchdog_expect_close = 0;
 	} else {
-		watchdog_trigger(data);
-		dev_crit(&data->client->dev,
-			"unexpected close, not stopping watchdog!\n");
+		if (!watchdog_trigger(data))
+			pr_crit("%s: unexpected close, not stopping watchdog!\n",
+				data->watchdog_name);
 	}
 
 	clear_bit(0, &data->watchdog_is_open);
-- 
2.53.0


             reply	other threads:[~2026-05-23  5:11 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-23  5:10 Chen-Shi-Hong [this message]
2026-05-23  5:44 ` [PATCH] hwmon: (fschmd) avoid client->dev dereference in watchdog_release sashiko-bot
2026-05-23 13:24 ` Guenter Roeck
2026-05-23 13:44   ` Chen-Shi-Hong

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