From: Jan Hudec <bulb@ucw.cz>
To: Om <okuttan@netd.com>
Cc: Rock Gordon <rockgordon@yahoo.com>,
linux-kernel@vger.kernel.org, kernelnewbies@nl.linux.org,
Bernd Petrovitsch <bernd@firmix.at>
Subject: Re: userspace vs. kernelspace address
Date: Sun, 30 Jan 2005 09:41:28 +0100 [thread overview]
Message-ID: <20050130084128.GA27925@vagabond> (raw)
In-Reply-To: <20050129042355.GA5527@netd.com>
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On Fri, Jan 28, 2005 at 20:23:55 -0800, Om wrote:
> On Fri, Jan 28, 2005 at 01:40:51PM -0800, Rock Gordon wrote:
> > Hi everbody,
> >
> > Thanks for your replies.
> >
> > However I think my copy_to_user and copy_from_user are
> > failing since the kernel-mode thread is copying data
> > into another process's address space, and I am not
> > sure how to do this. Do the get_fs() and set_fs()
> > combinations let you do that? If not, then how do I do
> My idea is on kernel thread is limited. But I think it is not possible to
> any userspace address from any kernel thread because they do not have access
> to it. Their proc_struct->mm field is empty.
Right. You can't access any user-space from kernel thread, because it
does not have any.
> I am not sure whether set_fs and get_fs help in this case.
Sure it can. set_fs(KERNEL_DS) sets things so, that if you pass kernel
address to copy_to/from_user, it will silently accept it and copy
to/from there.
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Jan 'Bulb' Hudec <bulb@ucw.cz>
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next prev parent reply other threads:[~2005-01-30 8:41 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20050128075209.GA14153@vagabond>
2005-01-28 21:40 ` userspace vs. kernelspace address Rock Gordon
2005-01-29 4:23 ` Om
2005-01-30 8:41 ` Jan Hudec [this message]
2005-01-30 15:37 ` Bernd Petrovitsch
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