Date: Wed, 28 Oct 2009 03:54:34 +0000 (GMT)
From: Dave Airlie <airlied@linux.ie>
To: David Miller <davem@davemloft.net>
cc: dri-devel@lists.sourceforge.net, andi@firstfloor.org,
       linux-kernel@vger.kernel.org, arnd@arndb.de
Subject: Re: is avoiding compat ioctls possible?
In-Reply-To: <20091027.204530.142024242.davem@davemloft.net>
Message-ID: <alpine.DEB.2.00.0910280353080.19088@skynet.skynet.ie>
References: <21d7e9970910272005mbb268r7b16493a22ca275a@mail.gmail.com> <20091027.203838.21218679.davem@davemloft.net> <alpine.DEB.2.00.0910280341331.19088@skynet.skynet.ie> <20091027.204530.142024242.davem@davemloft.net>
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> 
> > 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.
> 
> 2) Nobody has tested s390 yet :-)
> 

So will an inline like this work?

static inline void *__user convert_user_ptr(uint64_t ioctl_ptr)
{
#ifdef CONFIG_COMPAT
	if (is_compat_task())
		return compat_ptr((compat_uptr_t)ioctl_ptr);
	else
#endif
		return (void __user *)(unsigned long)ioctl_ptr;
}

then I can convert all the code to just use that instead of explicity 
casts or brokenness.

Dave.
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