From: Helge Hafting <helge.hafting@aitel.hist.no>
To: Tomko <tomko@haha.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: Why system call need to copy the date from the userspace before using it
Date: Thu, 14 Apr 2005 16:05:24 +0200 [thread overview]
Message-ID: <425E78A4.6090409@aitel.hist.no> (raw)
In-Reply-To: <425DD105.7010304@haha.com>
Tomko wrote:
> Catalin Marinas wrote:
>
>>
>> No, it is because this function checks whether the access to the user
>> space address is OK. There are situations when it can also sleep (page
>> not present).
>>
>>
>>
> what u means "OK"? kernel space should have right to access any
> memory address , can u expained in details what u means "OK"?
The user may not have any right to that memory, that means he
has no right to ask the kernel to mess with it either, even if the
kernel is authorized to do so.
Just as you can't ask a cop to jail someone. Sure, the cop has the power
to arrest, but he will check that there is reason to do so and not
automatically assume that you are right.
Helge Hafting
next prev parent reply other threads:[~2005-04-14 14:01 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-13 4:21 Why system call need to copy the date from the userspace before using it Tomko
2005-04-13 5:30 ` Vadim Lobanov
2005-04-13 10:29 ` Jan-Benedict Glaw
2005-04-13 10:43 ` Tomko
2005-04-13 11:10 ` Catalin Marinas
2005-04-14 2:10 ` Tomko
2005-04-14 2:18 ` David Schwartz
2005-04-14 14:05 ` Helge Hafting [this message]
2005-04-13 11:33 ` Benjamin Herrenschmidt
2005-04-13 11:59 ` Hacksaw
2005-04-13 12:40 ` Richard B. Johnson
2005-04-13 18:37 ` Theodore Ts'o
2005-04-13 19:20 ` Richard B. Johnson
2005-04-16 4:50 ` Hacksaw
2005-04-16 5:18 ` Vadim Lobanov
2005-04-16 8:30 ` Hacksaw
2005-04-16 19:35 ` Vadim Lobanov
2005-04-16 23:46 ` David Wagner
-- strict thread matches above, loose matches on Subject: below --
2005-04-13 6:48 Vadim Lobanov
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