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Date:   Wed, 23 Oct 2019 23:27:30 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Matthew Wilcox <willy@infradead.org>
cc:     Cyrill Gorcunov <gorcunov@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, linux-mm@kvack.org,
        Catalin Marinas <catalin.marinas@arm.com>, x86@kernel.org,
        Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH] x86/dumpstack/64: Don't evaluate exception stacks before
 setup
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On Wed, 23 Oct 2019, Matthew Wilcox wrote:

> On Wed, Oct 23, 2019 at 08:05:49PM +0200, Thomas Gleixner wrote:
> > Prevent this by checking the validity of the cea_exception_stack base
> > address and bailing out if it is zero.
> 
> Could also initialise cea_exception_stack to -1?  That would lead to it
> being caught by ...
> 
> >  	end = begin + sizeof(struct cea_exception_stacks);
> >  	/* Bail if @stack is outside the exception stack area. */
> >  	if (stk < begin || stk >= end)
> 
> this existing check.

Yes thought about that, but then decided to do it in a readable way :)