[PATCH v3 03/11] drm/i915: return EACCES for check_cmd() failures

[Chris Wilson]

On Mon, Aug 15, 2016 at 03:41:20PM +0100, Robert Bragg wrote:
> check_cmd() is checking whether a command adheres to certain
> restrictions that ensure it's safe to execute within a privileged batch
> buffer. Returning false implies a privilege problem, not that the
> command is invalid.
> 
> The distinction makes the difference between allowing the buffer to be
> executed as an unprivileged batch buffer or returning an EINVAL error to
> userspace without executing anything.

Ah, but you choose to actually execute it instead. We can't allow that
either.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre