linux-kernel - Re: [PATCH for-4.5] vfio: fix ioctl error handling

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Message-ID: <20160226134748.GL5273@mwanda>
Date:	Fri, 26 Feb 2016 16:47:48 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Alex Williamson <alex.williamson@...hat.com>,
	Baptiste Reynal <b.reynal@...tualopensystems.com>,
	Eric Auger <eric.auger@...aro.org>,
	Antonios Motakis <a.motakis@...tualopensystems.com>,
	Julia Lawall <Julia.Lawall@...6.fr>, kvm@...r.kernel.org
Subject: Re: [PATCH for-4.5] vfio: fix ioctl error handling

On Thu, Feb 25, 2016 at 01:34:43PM +0200, Michael S. Tsirkin wrote:
> Calling return copy_to_user(...) in an ioctl will not
> do the right thing if there's a pagefault:
> copy_to_user returns the number of bytes not copied
> in this case.
> 
> Fix up vfio to do
> 	if (copy_to_user(...))
> 		return -EFAULT;
> 
> everywhere.
> 
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>

Heh.  I don't exactly deserve this credit.

I have updated Smatch to check for this (will push next week probably).
I wouldn't have caught the issues in vfio_platform_common.c because
that's ARM only.

regards,
dan carpenter