Subject: Re: Bug: fio traps into kernel without exiting because futex has a
 deadloop
From: Peter Zijlstra <peterz@infradead.org>
To: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Darren Hart <dvhltc@us.ibm.com>,
       Rusty Russell <rusty@rustcorp.com.au>,
       LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <1245045817.2560.363.camel@ymzhang>
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Date: Mon, 15 Jun 2009 10:27:41 +0200
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On Mon, 2009-06-15 at 14:03 +0800, Zhang, Yanmin wrote:
> > +     ret = get_user_writeable(uaddr);
> X86 pte entry has no READABLE flag. Other platforms might have. If their pte
> only set WRITE flag, Is it poosible to create a similiar DOS attack with
> WRITEONLY area on such platforms?

I just checked a few such platforms and generic code, we seem to assume
read on write, and read when present in the generic code.

And those few platforms that supported wr-only also implemented that
(alpha, avr32 -- there might be more didn't go through all).


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