linux-kernel - Re: [PATCH v4 2/2] kunit: avoid memory leak on device register error

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Date: Fri, 19 Apr 2024 16:03:12 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Wander Lairson Costa <wander@...hat.com>
Cc: Brendan Higgins <brendan.higgins@...ux.dev>,
	David Gow <davidgow@...gle.com>, Rae Moar <rmoar@...gle.com>,
	Shuah Khan <skhan@...uxfoundation.org>,
	Matti Vaittinen <mazziesaccount@...il.com>,
	Maxime Ripard <mripard@...nel.org>,
	"open list:KERNEL UNIT TESTING FRAMEWORK (KUnit)" <linux-kselftest@...r.kernel.org>,
	"open list:KERNEL UNIT TESTING FRAMEWORK (KUnit)" <kunit-dev@...glegroups.com>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/2] kunit: avoid memory leak on device register error

On Fri, Apr 19, 2024 at 10:25:02AM -0300, Wander Lairson Costa wrote:
> If the device register fails, free the allocated memory before
> returning.
> 
> Signed-off-by: Wander Lairson Costa <wander@...hat.com>
> Fixes: d03c720e03bd ("kunit: Add APIs for managing devices")
> ---
>  lib/kunit/device.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/kunit/device.c b/lib/kunit/device.c
> index 25c81ed465fb..d8c09dcb3e79 100644
> --- a/lib/kunit/device.c
> +++ b/lib/kunit/device.c
> @@ -131,6 +131,7 @@ static struct kunit_device *kunit_device_register_internal(struct kunit *test,
>  	err = device_register(&kunit_dev->dev);
>  	if (err) {
>  		put_device(&kunit_dev->dev);
> +		kfree(kunit_dev);

This still looks wrong, the release function for the device should free
the memory here, not this kfree, as the reference count in the embedded
'struct device' handles the memory logic for the whole structure (if
not, then something is REALLY wrong...)

You _do_ have a release function for the device, right?  If not, you
should be getting loud messages in the kernel log when releasing a
device here.

thanks,

greg k-h