Re: is avoiding compat ioctls possible?

Andi Kleen
2009-10-28T03:51:18Z

On Tue, Oct 27, 2009 at 08:45:30PM -0700, David Miller wrote:
> From: Dave Airlie <airlied@linux.ie>
> Date: Wed, 28 Oct 2009 03:43:07 +0000 (GMT)
>
> > we already opencoded this (probably before it was macroisied or we just
> > pasted it), so the radeon one is buggy, I should just go and compat_* all
> > of these then and we should be all happy?
>
> It should be, it's only working because:
>
> 1) A malicious userland hasn't put garbage in the upper bits for
> you yet.

The x86 compat_ptr wouldn't even help with that because it doesn't mask.

If they use *_user() or anything else with access_ok later that should
be caught properly. The user land could only put in pointers to unmapped
[32bit...kernel boundary] data, which is harmless.

-Andi

--
ak@linux.intel.com -- Speaking for myself only.