linux-kernel - Re: [PATCH] samples/vfio-mdev: don't return zero on failure paths in mtty_dev

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Date:   Wed, 4 Jan 2017 08:30:41 -0700
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Kirti Wankhede <kwankhede@...dia.com>
Cc:     Alexey Khoroshilov <khoroshilov@...ras.ru>,
        Neo Jia <cjia@...dia.com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <ldv-project@...uxtesting.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH] samples/vfio-mdev: don't return zero on failure paths
 in mtty_dev_init()

On Wed, 4 Jan 2017 17:52:30 +0530
Kirti Wankhede <kwankhede@...dia.com> wrote:

> Dan Carpenter had sent similar change earlier.
> https://www.spinics.net/lists/kvm/msg141470.html
> 
> Alex,
> Did you pull that change in your tree?

I had somehow missed Dan's patch.  I'll apply Dan's with a Reported-by
credit for Alexey as well.  Thanks,

Alex

> On 12/31/2016 4:10 AM, Alexey Khoroshilov wrote:
> > If class_create() or mdev_register_device() fail, mtty_dev_init()
> > breaks off initialization, deallocates all resources, but returns zero.
> > 
> > The patch adds proper error code return values.
> > 
> > Found by Linux Driver Verification project (linuxtesting.org).
> > 
> > Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
> > ---
> >  samples/vfio-mdev/mtty.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
> > index 6b633a4ea333..e9c52e1f97a6 100644
> > --- a/samples/vfio-mdev/mtty.c
> > +++ b/samples/vfio-mdev/mtty.c
> > @@ -1446,6 +1446,7 @@ static int __init mtty_dev_init(void)
> >  	mtty_dev.vd_class = class_create(THIS_MODULE, MTTY_CLASS_NAME);
> >  
> >  	if (IS_ERR(mtty_dev.vd_class)) {
> > +		ret = PTR_ERR(mtty_dev.vd_class);
> >  		pr_err("Error: failed to register mtty_dev class\n");
> >  		goto failed1;
> >  	}
> > @@ -1458,7 +1459,8 @@ static int __init mtty_dev_init(void)
> >  	if (ret)
> >  		goto failed2;
> >  
> > -	if (mdev_register_device(&mtty_dev.dev, &mdev_fops) != 0)
> > +	ret = mdev_register_device(&mtty_dev.dev, &mdev_fops);
> > +	if (ret)
> >  		goto failed3;
> >  
> >  	mutex_init(&mdev_list_lock);
> > @@ -1467,11 +1469,9 @@ static int __init mtty_dev_init(void)
> >  	goto all_done;
> >  
> >  failed3:
> > -
> >  	device_unregister(&mtty_dev.dev);
> >  failed2:
> >  	class_destroy(mtty_dev.vd_class);
> > -
> >  failed1:
> >  	cdev_del(&mtty_dev.vd_cdev);
> >  	unregister_chrdev_region(mtty_dev.vd_devt, MINORMASK);
> >