linux-kernel - [PATCH v2] iio: trigger: Fix error handling in viio_trigger

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Message-Id: <20251106082923.32688-1-make24@iscas.ac.cn>
Date: Thu,  6 Nov 2025 16:29:23 +0800
From: Ma Ke <make24@...as.ac.cn>
To: jic23@...nel.org,
	dlechner@...libre.com,
	nuno.sa@...log.com,
	andy@...nel.org,
	error27@...il.com,
	andriy.shevchenko@...el.com
Cc: linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org,
	Ma Ke <make24@...as.ac.cn>,
	stable@...r.kernel.org
Subject: [PATCH v2] iio: trigger: Fix error handling in viio_trigger_alloc

viio_trigger_alloc() initializes the device with device_initialize()
but uses kfree() directly in error paths, which bypasses the device's
release callback iio_trig_release(). This could lead to memory leaks
and inconsistent device state.

Additionally, the current error handling has the following issues:
1. Potential double-free of IRQ descriptors when kvasprintf fails.
2. The release function may attempt to free negative subirq_base.
3. Missing mutex_destroy in release function.

Fix these issues by:
1. Replacing kfree(trig) with put_device(&trig->dev) in error paths.
2. Setting subirq_base to 0 after freeing IRQ descriptors in error
path to prevent double-free in release callback.
3. Modifying release function to properly handle negative subirq_base.
4. Adding missing mutex_destroy().

Found by code review.

Cc: stable@...r.kernel.org
Fixes: 2c99f1a09da3 ("iio: trigger: clean up viio_trigger_alloc()")
Signed-off-by: Ma Ke <make24@...as.ac.cn>
---
Changes in v2:
- modified the patch, thanks for developer's suggestions.
---
 drivers/iio/industrialio-trigger.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 54416a384232..9f6d30a244d9 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -524,6 +524,7 @@ static void iio_trig_release(struct device *device)
 			       CONFIG_IIO_CONSUMERS_PER_TRIGGER);
 	}
 	kfree(trig->name);
+	mutex_destroy(&trig->pool_lock);
 	kfree(trig);
 }

@@ -596,8 +597,9 @@ struct iio_trigger *viio_trigger_alloc(struct device *parent,

 free_descs:
 	irq_free_descs(trig->subirq_base, CONFIG_IIO_CONSUMERS_PER_TRIGGER);
+	trig->subirq_base = 0;
 free_trig:
-	kfree(trig);
+	put_device(&trig->dev);
 	return NULL;
 }

-- 
2.17.1