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

[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 <ville.syrjala at linux.intel.com>
>>>
>>> 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