linux-kernel - Re: [PATCH] x86/dumpstack/64: Don't evaluate exception stacks before setup

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Message-ID: <20191023183140.GC2963@bombadil.infradead.org>
Date:   Wed, 23 Oct 2019 11:31:40 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Cyrill Gorcunov <gorcunov@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>, linux-mm@...ck.org,
        Catalin Marinas <catalin.marinas@....com>, x86@...nel.org,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH] x86/dumpstack/64: Don't evaluate exception stacks before
 setup

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.