From: Jeff Dike <jdike@addtoit.com>
To: Blaisorblade <blaisorblade@yahoo.it>
Cc: luothing@sina.com, user-mode-linux-devel@lists.sourceforge.net
Subject: Re: Fixed - copy_from_user(dest, -1,...) hangs in TT mode (was: Re: [uml-devel] weak check of access_ok may lead hang!)
Date: Sat, 17 Sep 2005 13:00:02 -0400 [thread overview]
Message-ID: <20050917170002.GA5225@ccure.user-mode-linux.org> (raw)
In-Reply-To: <200509171734.36738.blaisorblade@yahoo.it>
On Sat, Sep 17, 2005 at 05:34:36PM +0200, Blaisorblade wrote:
> In fact, beyond this problem, we also fail to check whether the faulting
> address is under TASK_SIZE in TT mode on read accesses:
>
> #define access_ok_tt(type, addr, size) \
> ((type == VERIFY_READ) || (segment_eq(get_fs(), KERNEL_DS)) || \
> (((unsigned long) (addr) <= ((unsigned long) (addr) + (size))) && \
> (under_task_size(addr, size) || is_stack(addr, size))))
>
> See "(type == VERIFY_READ) || "do some real testing"? That's totally bogus.
>
> Jeff, what's that for? Not only the user can read on its own from kernel
> memory, we turn that into a feature and allow that as syscall parameter too?
> Waiting for an answer before fixing.
I think you're right. I don't see why that VERIFY_READ is there.
Jeff
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next prev parent reply other threads:[~2005-09-17 17:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20050916104057.77345.qmail@mail35-142.sinamail.sina.com.cn>
2005-09-17 15:34 ` Fixed - copy_from_user(dest, -1,...) hangs in TT mode (was: Re: [uml-devel] weak check of access_ok may lead hang!) Blaisorblade
2005-09-17 17:00 ` Jeff Dike [this message]
2005-09-17 17:00 ` Jeff Dike
2005-09-18 11:30 ` Blaisorblade
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