From: Linus Torvalds <torvalds@osdl.org>
To: Jesper Juhl <juhl-lkml@dif.dk>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] kill access_ok() call from copy_siginfo_to_user() that we might as well avoid.
Date: Mon, 20 Dec 2004 16:18:15 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.58.0412201617050.4112@ppc970.osdl.org> (raw)
In-Reply-To: <Pine.LNX.4.61.0412210025100.3581@dragon.hygekrogen.localhost>
On Tue, 21 Dec 2004, Jesper Juhl wrote:
>
> In kernel/signal.c::copy_siginfo_to_user() we are calling access_ok()
> unconditionally. As I see it there's no need for this since we might as
> well just call copy_to_user() instead of __copy_to_user() later on and
> then only get the overhead of the access_ok() check (inside
> copy_to_user())
No, the "access_ok()" is to protect the other side too, ie all the
"__put_user()" calls.
If you remove the access_ok(), you need to also change all the
__put_user() calls to "put_user()". And then the end result will be much
worse code than it is right now.
Linus
next prev parent reply other threads:[~2004-12-21 0:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-20 23:33 Jesper Juhl
2004-12-21 0:18 ` Linus Torvalds [this message]
2004-12-21 0:41 ` Jesper Juhl
[not found] ` <Pine.LNX.4.61.0412210145260.3581@dragon.hygekrogen.localhost>
2004-12-21 0:56 ` Linus Torvalds
2004-12-21 1:25 ` Jesper Juhl
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