linux-kernel - Re: [PATCH v4 07/18] nitro_enclaves: Init misc device providing the ioctl interface

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Message-ID: <20200629162013.GA718066@kroah.com>
Date:   Mon, 29 Jun 2020 18:20:13 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Andra Paraschiv <andraprs@...zon.com>
Cc:     linux-kernel@...r.kernel.org,
        Anthony Liguori <aliguori@...zon.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Colm MacCarthaigh <colmmacc@...zon.com>,
        Bjoern Doebel <doebel@...zon.de>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Frank van der Linden <fllinden@...zon.com>,
        Alexander Graf <graf@...zon.de>,
        Martin Pohlack <mpohlack@...zon.de>,
        Matt Wilson <msw@...zon.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Balbir Singh <sblbir@...zon.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Stewart Smith <trawets@...zon.com>,
        Uwe Dannowski <uwed@...zon.de>, kvm@...r.kernel.org,
        ne-devel-upstream@...zon.com
Subject: Re: [PATCH v4 07/18] nitro_enclaves: Init misc device providing the
 ioctl interface

On Mon, Jun 22, 2020 at 11:03:18PM +0300, Andra Paraschiv wrote:
> +static int __init ne_init(void)
> +{
> +	struct pci_dev *pdev = pci_get_device(PCI_VENDOR_ID_AMAZON,
> +					      PCI_DEVICE_ID_NE, NULL);
> +	int rc = -EINVAL;
> +
> +	if (!pdev)
> +		return -ENODEV;

Ick, that's a _very_ old-school way of binding to a pci device.  Please
just be a "real" pci driver and your probe function will be called if
your hardware is present (or when it shows up.)  To do it this way
prevents your driver from being auto-loaded for when your hardware is
seen in the system, as well as lots of other things.

> +
> +	if (!zalloc_cpumask_var(&ne_cpu_pool.avail, GFP_KERNEL))
> +		return -ENOMEM;
> +
> +	mutex_init(&ne_cpu_pool.mutex);
> +
> +	rc = pci_register_driver(&ne_pci_driver);

Nice, you did it right here, but why the above crazy test?

> +	if (rc < 0) {
> +		dev_err(&pdev->dev,
> +			"Error in pci register driver [rc=%d]\n", rc);
> +
> +		goto free_cpumask;
> +	}
> +
> +	return 0;

You leaked a reference on that pci device, didn't you?  Not good :(

thanks,

greg k-h