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Date:   Wed, 16 Jan 2019 14:21:41 +0100
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Gerd Hoffmann <kraxel@redhat.com>
Cc:     Frediano Ziglio <fziglio@redhat.com>,
        dri-devel@lists.freedesktop.org, David Airlie <airlied@linux.ie>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <virtualization@lists.linux-foundation.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <spice-devel@lists.freedesktop.org>,
        Dave Airlie <airlied@redhat.com>
Subject: Re: [Spice-devel] [PATCH 1/3] drm/qxl: add mode/framebuffer check
 functions
Message-ID: <20190116132141.GX10517@phenom.ffwll.local>
Mail-Followup-To: Gerd Hoffmann <kraxel@redhat.com>,
        Frediano Ziglio <fziglio@redhat.com>,
        dri-devel@lists.freedesktop.org, David Airlie <airlied@linux.ie>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" <virtualization@lists.linux-foundation.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" <spice-devel@lists.freedesktop.org>,
        Dave Airlie <airlied@redhat.com>
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On Wed, Jan 16, 2019 at 12:28:00PM +0100, Gerd Hoffmann wrote:
> > > +static int qxl_check_mode(struct qxl_device *qdev,
> > > +			  unsigned int width,
> > > +			  unsigned int height)
> > > +{
> > > +	if (width * height * 4 > qdev->vram_size)
> > 
> > Is someone checking for integer overflows already?
> 
> Need to have a look.  This is just ...

The addfb ioctl checks for integer overflows for you.
-Daniel

> 
> > > -	if (bo->surf.stride * bo->surf.height > qdev->vram_size) {
> > > -		DRM_ERROR("Mode doesn't fit in vram size (vgamem)");
> > > -		return -EINVAL;
> > > -	}
> 
> ... that check moved into the new function.
> 
> cheers,
>   Gerd
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch