linux-kernel - Re: [PATCH v3 2/2] kunit: avoid memory leak on device register error

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Date: Fri, 19 Apr 2024 12:58:44 +0800
From: David Gow <davidgow@...gle.com>
To: Wander Lairson Costa <wander@...hat.com>
Cc: Brendan Higgins <brendan.higgins@...ux.dev>, Rae Moar <rmoar@...gle.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Shuah Khan <skhan@...uxfoundation.org>, 
	Maxime Ripard <mripard@...nel.org>, Matti Vaittinen <mazziesaccount@...il.com>, 
	"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 v3 2/2] kunit: avoid memory leak on device register error

On Fri, 19 Apr 2024 at 05:02, Wander Lairson Costa <wander@...hat.com> 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")
> ---

Thanks.

I'm not sure this is correct, though... Shouldn't put_device() free this for us?

The documentation for device_register() says to never free a device
after device_register() has been called, even if it fails:
https://docs.kernel.org/driver-api/infrastructure.html#c.device_register

Or am I missing something?

Cheers,
-- David


>  lib/kunit/device.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/lib/kunit/device.c b/lib/kunit/device.c
> index 25c81ed465fb..bc2e2032e505 100644
> --- a/lib/kunit/device.c
> +++ b/lib/kunit/device.c
> @@ -119,10 +119,8 @@ static struct kunit_device *kunit_device_register_internal(struct kunit *test,
>         kunit_dev->owner = test;
>
>         err = dev_set_name(&kunit_dev->dev, "%s.%s", test->name, name);
> -       if (err) {
> -               kfree(kunit_dev);
> -               return ERR_PTR(err);
> -       }
> +       if (err)
> +               goto error;
>
>         kunit_dev->dev.release = kunit_device_release;
>         kunit_dev->dev.bus = &kunit_bus_type;
> @@ -131,7 +129,7 @@ static struct kunit_device *kunit_device_register_internal(struct kunit *test,
>         err = device_register(&kunit_dev->dev);
>         if (err) {
>                 put_device(&kunit_dev->dev);
> -               return ERR_PTR(err);
> +               goto error;
>         }
>
>         kunit_dev->dev.dma_mask = &kunit_dev->dev.coherent_dma_mask;
> @@ -140,6 +138,9 @@ static struct kunit_device *kunit_device_register_internal(struct kunit *test,
>         kunit_add_action(test, device_unregister_wrapper, &kunit_dev->dev);
>
>         return kunit_dev;
> +error:
> +       kfree(kunit_dev);
> +       return ERR_PTR(err);
>  }
>
>  /*
> --
> 2.44.0
>

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