Re: [Intel-gfx] drm-next xf86-video-vmware breakage Was [PATCH 02/10] drm/uapi: Validate the mode flags/type

2018-03-21 Thread Thomas Hellstrom 

On 03/21/2018 09:51 PM, Ville Syrjälä wrote:

On Wed, Mar 21, 2018 at 09:45:09PM +0100, Thomas Hellstrom wrote:

Hi, Ville,

On 11/14/2017 07:32 PM, Ville Syrjala wrote:

From: Ville Syrjälä 

Currently userspace is allowed to feed in any king of garbage in the
high bits of the mode flags/type, as are drivers when probing modes.
Reject any mode with bogus flags/type.

Hopefully this won't break any current userspace...

Unfortunately this breaks xf86-video-vmware which currently leaves the
mode->type uninitialized :(.
That code is inherited from the old gallium xorg state tracker. I don't
know whether it has spread elsewhere but the symptoms are that the X
server frequently dies failing to set screen resources, a very
uninformative error.

I'll fix the xf86-video-vmware driver, but I guess we need to back out
the mode->type check.

Dang. So the flags check is fine but type check is not?

Yes, we copy the flags field untranslated from xorg's 
DisplayModePtr::Flags field which seems to be what 
xf86-video-modesetting does as well, so I guess we should be OK there.


/Thomas


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Re: [Intel-gfx] drm-next xf86-video-vmware breakage Was [PATCH 02/10] drm/uapi: Validate the mode flags/type

2018-03-21 Thread Ville Syrjälä 
On Wed, Mar 21, 2018 at 09:45:09PM +0100, Thomas Hellstrom wrote:
> Hi, Ville,
> 
> On 11/14/2017 07:32 PM, Ville Syrjala wrote:
> > From: Ville Syrjälä 
> >
> > Currently userspace is allowed to feed in any king of garbage in the
> > high bits of the mode flags/type, as are drivers when probing modes.
> > Reject any mode with bogus flags/type.
> >
> > Hopefully this won't break any current userspace...
> 
> Unfortunately this breaks xf86-video-vmware which currently leaves the 
> mode->type uninitialized :(.
> That code is inherited from the old gallium xorg state tracker. I don't 
> know whether it has spread elsewhere but the symptoms are that the X 
> server frequently dies failing to set screen resources, a very 
> uninformative error.
> 
> I'll fix the xf86-video-vmware driver, but I guess we need to back out 
> the mode->type check.

Dang. So the flags check is fine but type check is not?

-- 
Ville Syrjälä
Intel OTC
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