linux-kernel - Re: [PATCH 3/5] exec: unify compat_do

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Date:	Sat, 26 Feb 2011 13:57:31 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>, pageexec@...email.hu,
	Solar Designer <solar@...nwall.com>,
	Eugene Teo <eteo@...hat.com>,
	Brad Spengler <spender@...ecurity.net>,
	Roland McGrath <roland@...hat.com>,
	Milton Miller <miltonm@....com>
Subject: Re: [PATCH 3/5] exec: unify compat_do_execve() code

On 02/26, Oleg Nesterov wrote:
>
> Once again, to me "void __user*" looks better (just simpler). In this
> case get_arg_ptr() becomes (without const/__user for the clarity)
>
> 	void *get_arg_ptr(void **argv, int argc, bool compat)
> 	{
> 		char *ptr;
>
> 	#ifdef CONFIG_COMPAT
> 		if (unlikely(compat)) {
> 			compat_uptr_t *a = argv;
> 			compat_uptr_t p;
>
> 			if (get_user(p, a + argc))
> 				return ERR_PTR(-EFAULT);
>
> 			return compat_ptr(p);
> 		}
> 	#endif
>
> 		if (get_user(ptr, argv + argc))
> 			return ERR_PTR(-EFAULT);
>
> 		return ptr;
> 	}
>
> Otherwise, get_arg_ptr() should return conditional_user_ptr_t as well,

No, this is not true, I am stupid.

Still,

> this looks like the unnecessary complication to me, but of course this
> is subjective.
>
> So, what do you think?

Yes, please.

Oleg.

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