Message-ID: <543D2D66.7040000@martingkelly.com>
Date: Tue, 14 Oct 2014 07:04:22 -0700
From: Martin Kelly <martin@martingkelly.com>
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To: David Vrabel <david.vrabel@citrix.com>, xen-devel@lists.xenproject.org,
        x86@kernel.org, linux-kernel@vger.kernel.org
CC: konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, tglx@linutronix.de,
        mingo@redhat.com, Martin Kelly <martkell@amazon.com>
Subject: Re: [PATCH] xen/setup: add paranoid index check and warning
References: <1413249548-26415-1-git-send-email-martin@martingkelly.com> <543CEB56.3080009@citrix.com>
In-Reply-To: <543CEB56.3080009@citrix.com>
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On 10/14/2014 02:22 AM, David Vrabel wrote:
> On 14/10/14 02:19, Martin Kelly wrote:
>> In a call to set_phys_range_identity, i-1 is used without checking that
>> i is non-zero. Although unlikely, a bug in the code before it could
>> cause the value to be 0, leading to erroneous behavior. This patch adds
>> a check against 0 value and a corresponding warning.
> 
> This can only happen if the toolstack supplies a memory map with zero
> entries.  I could see justification for adding a panic at the top of
> this function in this case, but I can't see the usefulness of this warning.
> 

Yes, a panic is probably appropriate. What do you think about the relative merits of panicing in the callers vs. in the sanitize_e820_map function itself (thus to avoid a bunch of similar error checks in the callers)?
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