From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Fan Wu <fanwu01@zju.edu.cn>,
	Guenter Roeck <linux@roeck-us.net>
Subject: [PATCH 6.18 1058/1250] hwmon: (gpio-fan) Fix use-after-free in alarm work
Date: Thu, 17 Sep 2026 16:14:13 +0100
Message-ID: <20260917151620.800980405@linuxfoundation.org>
In-Reply-To: <20260917151551.901433442@linuxfoundation.org>
References: <20260917151551.901433442@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Fan Wu <fanwu01@zju.edu.cn>

commit a2471ed17b0e6ff7bfb6b2ea8e6e5b04c309d293 upstream.

fan_alarm_irq_handler() queues fan_data->alarm_work, but nothing
cancels it.  fan_alarm_notify() dereferences fan_data and its hwmon
device.  On unbind, devres frees the interrupt, which only waits for
the handler itself, and then releases the hwmon device and fan_data,
so a pending fan_alarm_notify() can run after those frees.

Replace INIT_WORK() with devm_work_autocancel(), registered before
devm_request_irq().  The devres cleanup then frees the interrupt
first, so no new work can be queued, and cancels the work while
fan_data and the hwmon device are still alive.

This issue was found by an in-house static analysis tool.

Fixes: d6fe1360f42e ("hwmon: add generic GPIO fan driver")
Cc: stable@vger.kernel.org
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <fanwu01@zju.edu.cn>
Link: https://patch.msgid.link/20260819033317.446191-1-fanwu01@zju.edu.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/hwmon/gpio-fan.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/hwmon/gpio-fan.c
+++ b/drivers/hwmon/gpio-fan.c
@@ -12,6 +12,7 @@
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/devm-helpers.h>
 #include <linux/platform_device.h>
 #include <linux/err.h>
 #include <linux/kstrtox.h>
@@ -84,6 +85,7 @@ static DEVICE_ATTR_RO(fan1_alarm);
 static int fan_alarm_init(struct gpio_fan_data *fan_data)
 {
 	int alarm_irq;
+	int err;
 	struct device *dev = fan_data->dev;
 
 	/*
@@ -94,7 +96,11 @@ static int fan_alarm_init(struct gpio_fa
 	if (alarm_irq <= 0)
 		return 0;
 
-	INIT_WORK(&fan_data->alarm_work, fan_alarm_notify);
+	err = devm_work_autocancel(dev, &fan_data->alarm_work,
+				   fan_alarm_notify);
+	if (err)
+		return err;
+
 	irq_set_irq_type(alarm_irq, IRQ_TYPE_EDGE_BOTH);
 	return devm_request_irq(dev, alarm_irq, fan_alarm_irq_handler,
 				IRQF_SHARED, "GPIO fan alarm", fan_data);