From: Brian Gerst <bgerst@didntduck.org>
To: nataraja kumar <hainattu@yahoo.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: A question on kernel stack
Date: Fri, 21 Feb 2003 13:27:40 -0500 [thread overview]
Message-ID: <3E566F9C.7010406@didntduck.org> (raw)
In-Reply-To: <20030221180508.18214.qmail@web20206.mail.yahoo.com>
nataraja kumar wrote:
> hi,
> my apologies if i am wrong. please let me know
> why does kernel use kernel stack when process jumps
> from user mode to kernel mode. why can't user stack
> be used ?
>
> nattu.
1) The user stack could be invalid. An invalid stack in the kernel will
cause the processor to double fault (see the recent double fault thread).
2) Security. You could set up the stack pointer from userspace so that
the kernel would overwrite memory that userspace can't access.
3) Security #2. You don't want to give userspace access to certain data
written to the stack in kernel mode.
--
Brian Gerst
next prev parent reply other threads:[~2003-02-21 18:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-21 18:05 A question on kernel stack nataraja kumar
2003-02-21 18:09 ` Oliver Neukum
2003-02-21 18:27 ` Brian Gerst [this message]
2003-02-21 19:25 ` Richard B. Johnson
2003-02-23 7:43 ` cs02m023
2003-02-23 14:33 ` Kasper Dupont
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